A back-mixing prevention high-speed dispersing device, a dispersing pipe, and a continuous production device and process for water-based hydroxyl acrylic dispersion

Abstract

The application discloses a kind of anti-back mixing high-speed dispersion device, dispersion pipe, and a kind of water-based hydroxyl acrylic dispersion continuous production device and process.The anti-back mixing high-speed dispersion device includes the following components: dispersion stator and cap type dispersion turntable, the upper portion of dispersion stator is provided with clamping groove, the lower portion of cap type dispersion turntable is provided with dispersion tooth, clamping groove and dispersion tooth are engaged;The inner wall of clamping groove is provided with feed port, and the outer wall of clamping groove is provided with discharge port.The anti-back mixing high-speed dispersion device and dispersion pipe of the application can quickly and efficiently neutralize and disperse prepolymer in continuous mode, effectively improve mixing and shearing efficiency, have high dispersion uniformity, the size distribution range of dispersed particle is narrow, and the phenomenon of uneven residence time caused by prepolymer back mixing is avoided.The continuous hydroxypropyl production process and device of the application can realize the rapid and efficient continuous production of multiple varieties of water-based hydroxypropyl dispersion, completely realize automation, have low energy consumption, low production cost and stable product quality.

Description

Technical Field

[0001] This invention belongs to the field of dispersion equipment, specifically relating to continuous production dispersion equipment and continuous process for aqueous hydroxyl acrylic resin dispersions. Background Technology

[0002] With increasing public awareness of environmental protection and increasingly stringent environmental regulations, the issue of VOC (volatile organic compound) emissions has gradually attracted attention. Waterborne hydroxy acrylic resins, using water as the dispersion medium, have experienced rapid development due to their excellent properties such as environmental friendliness, light resistance, aging resistance, and chemical resistance, as well as relatively low production costs. They have become the largest-volume resin in the waterborne coatings industry. They are widely used for coating and protection in industrial and civilian fields such as aircraft, automobiles, instruments and equipment, construction, and furniture. Compared with traditional solvent-based coatings, waterborne hydroxy acrylic resin dispersions use water instead of organic solvents as the dispersion medium, containing only a small amount of volatile organic solvents, making them a low-toxicity, low-odor organic polymer coating.

[0003] Currently, the industrial production of aqueous dispersions of hydroxyl acrylic resins mainly relies on batch reactors. After the hydroxyl acrylic prepolymer is synthesized in a prepolymer reactor, it is cooled and then transferred in batches to a dispersion reactor for neutralization. Dispersion water is then gradually added, and after successful dispersion, the mixture is transferred to a buffer tank. This process suffers from low production efficiency, high energy consumption, batch-to-batch product variations, and unstable production. Furthermore, the reactors must be washed after each batch dispersion, resulting in excessive waste liquid.

[0004] Patent CN102164660B provides a semi-continuous production method in which the hydroxyacrylic acid prepolymer is synthesized in a batch reactor and then dispersed by a high-speed mixing pump. This method has low efficiency in synthesizing hydroxyacrylic acid prepolymer, low viscosity, wide particle size distribution, and is prone to bimodalization. The emulsion is unstable and prone to stratification after long-term storage. At present, the production process of removing organic solvents from waterborne polyurethane dispersions in industry is mainly based on the batch method. The batch process refers to the process in which the prepolymerization, chain extension, dispersion, and solvent removal processes are carried out step by step in the reactor in time sequence after one feeding. However, the batch process has significant disadvantages in the production of waterborne polyurethane dispersions, as follows: (1) low production efficiency, high equipment vacancy rate, and high production cost; (2) excessive reliance on manual labor and low degree of automation; (3) large quality fluctuations between product batches and high defect rate.

[0005] Patent CN109824913B discloses a continuous dispersion device for waterborne polyurethane dispersions, relating to a continuous dispersion system for waterborne polyurethane dispersions, its continuous dispersion process, and applications. The continuous dispersion system includes a tubular disperser with a feed inlet and multiple water inlets. It also includes a motor and multiple toothed dispersion discs driven by the motor and located on the central shaft inside the tubular disperser. This system enables the dispersion of high-viscosity prepolymers, achieving continuous production. The tubular system uses an internal partition plate to prevent back-mixing of materials. The partition plate has relatively small gaps; however, due to its static nature, dead zones exist, and the gaps are prone to crusting and blockage, as well as excessive pressure loss. Frequent cleaning is required during use.

[0006] Patent CN108097194A provides a continuous production system, a continuous production process, and applications for preparing waterborne polyurethane dispersions. The continuous production process includes: obtaining prepolymer I by reacting polyisocyanate and oligomeric polyol in a first tubular reactor VR1; adding the oligomeric polyol in four parts to VR1; obtaining prepolymer II by reacting prepolymer I with a nonionic hydrophilic compound in a second tubular reactor VR2; adding the nonionic hydrophilic compound in three parts to VR2; diluting prepolymer II with a solvent in VR3; reacting the diluted prepolymer with a hydrophilic chain extender and a small-molecule diamine in VR4; and emulsifying and dispersing in VR5. This process enables rapid and efficient continuous production of waterborne polyurethane dispersions. However, the equipment provided by this process is complex, contains many internal mixing components, and has relatively small connecting pipe diameters between each mixer, leading to excessive material pressure loss, easy clogging, and difficulty in controlling the internal temperature of each mixing unit. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the present invention aims to provide a high-speed dispersion device and dispersion tube for preventing back-mixing, as well as a continuous production device and process for water-based hydroxyacrylic acid dispersions. This dispersion equipment and process enables rapid and efficient continuous production of dispersions, achieving full automation. It offers advantages such as low energy consumption, low production costs, and stable product quality. It effectively solves industry problems in traditional water-based hydroxyacrylic acid production processes, such as low production efficiency, difficulty in temperature control, high viscosity, slag discharge, high fineness, and the need for large amounts of cleaning solvents. This significantly improves the production efficiency of water-based hydroxyacrylic acid while reducing operating costs and equipment investment.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A high-speed dispersion device for preventing back-mixing includes the following components: a dispersion stator 17 and a cap-type dispersion turntable 18. The upper part of the dispersion stator is provided with a slot, and the lower part of the cap-type dispersion turntable is provided with dispersion teeth. The slot and the dispersion teeth mesh with each other. The inner wall of the slot is provided with a feed inlet 23, and the outer wall of the slot is provided with a discharge outlet 24.

[0010] As a preferred embodiment, the inner wall of the card slot is provided with 3-5 inlet ports; the outer wall of the card slot is provided with 3-5 outlet ports.

[0011] As a preferred option, the intermeshing grooves and dispersing teeth can be one, two, three, four or more sets.

[0012] As a preferred embodiment, a set of dispersion teeth consists of 15-30 teeth, preferably 18-25 teeth; the length of the dispersion teeth is 1-3cm, and the thickness of the dispersion teeth is 0.7-2mm.

[0013] As a preferred option, the card slot width is 1-3mm and the depth is 1-3.5cm.

[0014] As a preferred embodiment, the width of the inlet or outlet is 1-2.5 mm.

[0015] A high-speed dispersion tube for preventing back-mixing includes the following components: a tube, a high-speed dispersion device for preventing back-mixing, a flat-plate sawtooth dispersion disc 22, a bottom inlet 13, a top outlet 19, a wall inlet, and a drive shaft; wherein, a cap-type dispersion disc is fixed on the drive shaft, a dispersion stator is fixed on the inner wall of the tube, the wall inlet is located at the lower part of the high-speed dispersion device for preventing back-mixing, and the flat-plate sawtooth dispersion disc 22 is located at the lower part of the high-speed dispersion device for preventing back-mixing.

[0016] As a preferred embodiment, the anti-back-mixing high-speed dispersion tube has 2-5 stages of anti-back-mixing high-speed dispersion device.

[0017] As a preferred option, there is a cavity between the two adjacent anti-back-mixing high-speed dispersion devices.

[0018] As a preferred embodiment, the lower part of the primary anti-back-mixing high-speed dispersion device located at the bottom of the anti-back-mixing high-speed dispersion tube does not have a flat-plate sawtooth dispersion disc 22.

[0019] The anti-backmixing high-speed dispersion device and dispersion tube can quickly and efficiently neutralize and disperse prepolymers continuously, significantly improving effective mixing and shearing efficiency, resulting in high dispersion uniformity and a narrow particle size distribution range. At the same time, it avoids the uneven residence time phenomenon caused by prepolymer backmixing.

[0020] A continuous production apparatus for aqueous hydroxyacrylic acid dispersion includes the following components: a hydroxypropyl first-stage monomer feed tank 1, a first-stage monomer continuous polymerization reactor 2, an initiator feed tank 3, a second-stage monomer feed tank 4, a second-stage monomer continuous polymerization reactor 5, a viscosity reducing water feed tank 6, a neutralizing agent feed tank 7, a dispersion water feed tank 8, a post-treatment tubular reactor with static mixing 9, a cooling pipe with static mixing 10, a back-mixing anti-high-speed dispersion pipe 11, and a finished product storage tank 12, wherein the back-mixing anti-high-speed dispersion pipe 11 is equipped with a 3-stage back-mixing anti-high-speed dispersion device from bottom to top.

[0021] In the continuous production apparatus for aqueous hydroxyacrylic acid dispersions of the present invention, the bottom outlet of the first-stage monomer feed tank 1 is connected to the first-stage monomer continuous polymerization reactor 2. The bottom outlet of the initiator feed tank 3 is connected to both the first-stage monomer continuous polymerization reactor 2 and the second-stage monomer continuous polymerization reactor 5. The bottom outlet of the second-stage monomer feed tank 4 is connected to the second-stage monomer continuous polymerization reactor 5. The bottom outlet of the first-stage monomer continuous polymerization reactor 2 is connected to the upper inlet of the second-stage monomer continuous polymerization reactor 5. The bottom outlet of the second-stage monomer continuous polymerization reactor 5 is connected to a post-treatment tubular reactor 9 with static mixing, then to a cooling pipe 10 with static mixing, then to the bottom inlet 13 of a high-speed dispersion pipe 11 to prevent backmixing, and the top outlet 19 of the pipe is connected to a finished product storage tank 12.

[0022] In the continuous production apparatus for waterborne hydroxy acrylic dispersions of the present invention, the viscosity reducing water inlet tank 6 is connected to the inlet 14 of the anti-back-mixing high-speed dispersion pipe 11, the neutralizing agent inlet tank 7 is connected to the inlet 15 of the anti-back-mixing high-speed dispersion pipe 11, and the dispersion water inlet tank 8 is connected to the inlet 16 of the anti-back-mixing high-speed dispersion pipe 11.

[0023] This invention provides a process for preparing a low-solvent aqueous hydroxy acrylic acid dispersion. The method uses the aforementioned apparatus and includes the following steps:

[0024] 1) The temperature of the first-stage monomer continuous polymerization reactor 2 is raised to 138-142℃, the stirring is turned on and the speed is maintained at 140-160 rpm, and then the reaction is continuously added through the hydroxypropyl first-stage monomer feed tank 1. The residence time of the monomer in the reactor is 4.5-5.5h.

[0025] 2) The temperature of the two-stage continuous monomer polymerization reactor 5 is raised to 138-142℃. The prepolymer from the one-stage continuous monomer polymerization reactor 2 enters the two-stage continuous monomer polymerization reactor 5. At the same time, the two-stage monomer is added dropwise from the two-stage monomer feed tank 4 to the two-stage continuous monomer polymerization reactor 5. Stirring is started at the same time, and the temperature is maintained at 138-142℃. The average residence time of the prepolymer is 1-2 hours. The stirring speed is 140-160 rpm.

[0026] 3) The product from the two-stage monomer continuous polymerization reactor enters the post-treatment tubular reactor 9 with static mixing, where it stays for 1-1.5 hours and the temperature is maintained at 138-142℃.

[0027] 4) The product from step 3) enters the cooling tube 10 with static mixing and is cooled to 110-120℃; then it enters the bottom inlet 13 of the anti-backmixing high-speed dispersion tube 11, the viscosity reducing water enters the tube wall inlet 14 of the anti-backmixing high-speed dispersion tube 11, the neutralizing agent enters the tube wall inlet 15 of the anti-backmixing high-speed dispersion tube 11, and the dispersion water enters the tube wall inlet 16 of the anti-backmixing high-speed dispersion tube 11.

[0028] In step 4), after the product from step 3) is cooled, it first passes through the first-stage anti-back-mixing high-speed dispersion device with viscosity-reducing water and then enters the first chamber, where it is initially mixed with the neutralizing agent. Then it passes through the second-stage anti-back-mixing high-speed dispersion device and enters the second chamber, where it is initially mixed and dispersed with dispersion water. Then it passes through the third-stage anti-back-mixing high-speed dispersion device and finally enters the finished product storage tank.

[0029] Preferably, the dropping rate of the monomer segment is 350-450 L / min.

[0030] Preferably, the reaction temperature of the single-stage monomer continuous polymerization reactor is 138-142℃.

[0031] Preferably, the reaction residence time in the monomer continuous polymerization reactor is 4.5-5.5 h.

[0032] Preferably, the stirring speed of the monomer continuous polymerization reactor is 155-165 rpm.

[0033] Preferably, the dropping rate of the two monomers is 80-150 g / min.

[0034] Preferably, the reaction temperature of the two-stage monomer continuous polymerization reactor is 138-142℃.

[0035] Preferably, the reaction residence time in the two-stage monomer continuous polymerization reactor is 1.2-1.5 h.

[0036] Preferably, the stirring speed of the two-stage monomer continuous polymerization reactor is 155-165 rpm.

[0037] Preferably, the proportion of the dispersed water is 20-25% of the total water volume.

[0038] Preferably, the rotational speed of the anti-back-mixing high-speed dispersion tube 11 is 1000-1300 rpm.

[0039] Preferably, the monomer in the hydroxypropyl monomer feed tank 1 comprises one or more of the following: n-butyl acrylate (BA), butyl methacrylate (BMA), methyl methacrylate (MMA), hydroxypropyl acrylate (HPA), styrene (ST), hydroxyethyl methacrylate (HEMA), and ethylene glycol butyl ether (BCS).

[0040] Preferably, the initiator is one or more of benzoyl peroxide (BPO), sodium dodecyl sulfate (SDS), di-tert-butyl peroxide (DTBP), di-tert-pentyl peroxide (DTAP), and tert-butyl hydrogen peroxide (T-BHP).

[0041] Preferably, the monomer in the two-stage monomer feed tank 4 comprises one or more of butyl methacrylate (BMA), hydroxyethyl methacrylate (HEMA), n-butyl acrylate (BA), and acrylic acid (AA).

[0042] Preferably, the neutralizing agent is N,N'-dimethylethanolamine (DMEA).

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) The continuous production method improves production efficiency by 300% compared to the existing intermittent production method;

[0045] (2) The unit energy consumption is reduced by 50% by continuous production compared with the existing intermittent production method;

[0046] (3) It reduces the consumption of washing solvent and the generation of waste liquid;

[0047] (4) The continuous production method has significantly improved product quality, such as product fineness, slag content and solvent content, compared with the existing intermittent production method.

[0048] This invention's production process enables rapid, efficient, and continuous production of multiple varieties of hydroxyacrylic acid dispersions, achieving full automation with low energy consumption, low production costs, and stable product quality. It effectively solves industry problems associated with traditional water-based hydroxyacrylic acid dispersion production, such as slow production processes, long heating and cooling times, poor temperature control, slag discharge, high fineness, and high prepolymer dispersion viscosity, significantly improving production efficiency and reducing operating costs and equipment investment. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the continuous production process of low-solvent hydroxy acrylic acid in the examples;

[0050] 1. Hydroxypropyl first-stage monomer feed tank; 2. First-stage monomer continuous polymerization reactor; 3. Initiator feed tank; 4. Second-stage monomer feed tank; 5. Second-stage monomer continuous polymerization reactor; 6. Viscosity reducer feed tank; 7. Neutralizer feed tank; 8. Dispersion water feed tank; 9. Post-treatment tubular reactor with static mixing; 10. Cooling pipe with static mixing; 11. Anti-backmixing high-speed dispersion pipe; 12. Finished product storage tank.

[0051] Figure 2 Schematic diagram of the anti-back-mixing high-speed dispersion tube structure in the embodiment;

[0052] 13. Bottom inlet of the pipe; 14. Viscosity reducing water inlet of the pipe wall; 15. Neutralizing agent inlet of the pipe wall; 16. Dispersing water inlet of the pipe wall; 17. Dispersing stator; 18. Cap-type dispersing disc; 19. Top outlet of the pipe; 20. Mechanical seal; 21. Jacket; 22. Dispersing disc.

[0053] Figure 3 This is a schematic diagram of the 18-hat type dispersion turntable structure in the embodiment;

[0054] Figure 4 Here is a schematic diagram of the structure of the dispersed stator 17 in the embodiment:

[0055] 23. Feed inlet, 24. Discharge outlet. Detailed Implementation

[0056] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited thereto.

[0057] The testing method used in this embodiment of the invention:

[0058] Residue content: Take 500g of dispersion sample, filter it through a 200-mesh filter, dry it, and weigh it.

[0059] Fineness: Take 1g of sample and observe the fineness of the dispersion by passing it through a fineness scraper.

[0060] Particle size: Take 0.1g of sample, dilute it 1500 times, and then test the particle size of the sample using a particle size analyzer.

[0061] Solid content: Take 1.05g of dispersion with tin foil and put it into a high-temperature oven at 150℃ for 30 minutes.

[0062] Solvent content: 50g of sample was used for headspace gas chromatography; Gas chromatograph model: Agilent Technologies 7890B; Main parameters: Column: DB-WAX (30m x 0.25mm x 0.25μm); Injector temperature: 200℃, Split ratio: 50:1, Pressure: 76.025psi, Septum purge flow rate: 3ml / min; Column flow rate: 1ml / min constant flow rate.

[0063] Viscosity: Take 100g of the dispersion in a disposable plastic cup and test it with a viscometer with rotor model 63.

[0064] Pendulum hardness: Using a paint film pendulum hardness tester, place the glass test plate coated with paint film on a horizontal workbench, then slowly lower the pendulum onto the test plate, deflect the pendulum by 5.5°, release the pendulum and let it swing freely. When the pendulum reaches 5°, start timing and record the time it takes for the swing amplitude to decrease from 5° to 2°. Measure at three different positions, and finally calculate the average of the three values ​​using a formula.

[0065] Transparency: Using a transparency meter - TMD type, the solution to be tested is placed in a dry and clean liquid tank, then the measuring port is inserted, and the value displayed on the instrument is read, which is the transparency of the substance.

[0066] Gloss: The gloss of the paint film is measured using a gloss meter. First, the instrument is calibrated with a black standard plate. After the gloss meter is calibrated and adjusted, three data points are measured at different positions parallel to the coating direction of the sample, and the average value is recorded as the gloss value.

[0067] Example 1

[0068] A continuous production unit for waterborne hydroxyacrylic acid dispersion includes the following components: a first-stage monomer feed tank 1, a first-stage monomer continuous polymerization reactor 2, an initiator feed tank 3, a second-stage monomer feed tank 4, a second-stage monomer continuous polymerization reactor 5, a viscosity reducing water feed tank 6, a neutralizing agent feed tank 7, a dispersion water feed tank 8, a post-treatment tubular reactor with static mixing 9, a cooling pipe with static mixing 10, a back-mixing anti-high-speed dispersion pipe 11, and a finished product storage tank 12. The back-mixing anti-high-speed dispersion pipe 11 is equipped with a 3-stage back-mixing anti-high-speed dispersion device from bottom to top.

[0069] In the continuous production unit of aqueous hydroxyacrylic acid dispersion, the bottom outlet of the first-stage monomer feed tank 1 is connected to the first-stage monomer continuous polymerization reactor 2. The initiator feed tank 3 is connected to both the first-stage monomer continuous polymerization reactor 2 and the second-stage monomer continuous polymerization reactor 5. The bottom outlet of the second-stage monomer feed tank 4 is connected to the second-stage monomer continuous polymerization reactor 5. The bottom outlet of the first-stage monomer continuous polymerization reactor 2 is connected to the upper inlet of the second-stage monomer continuous polymerization reactor 5. The bottom outlet of the second-stage monomer continuous polymerization reactor 5 is connected to the post-treatment tubular reactor 9 with static mixing, then to the cooling pipe 10 with static mixing, then to the bottom inlet 13 of the anti-backmixing high-speed dispersion pipe 11, and the top outlet 19 of the pipe is connected to the finished product storage tank 12.

[0070] In the continuous production unit of waterborne hydroxy acrylic acid dispersion, the viscosity reducing water inlet tank 6 is connected to the inlet 14 of the anti-back-mixing high-speed dispersion pipe 11, the neutralizing agent inlet tank 7 is connected to the inlet 15 of the anti-back-mixing high-speed dispersion pipe 11, and the dispersion water inlet tank 8 is connected to the inlet 16 of the anti-back-mixing high-speed dispersion pipe 11.

[0071] The anti-back-mixing high-speed dispersion device includes the following components: a dispersion stator 17 and a cap-type dispersion turntable 18. The upper part of the dispersion stator is provided with a slot, and the lower part of the cap-type dispersion turntable is provided with dispersion teeth. The slot and the dispersion teeth mesh. The inner wall of the slot is provided with a feed inlet 23, and the outer wall of the slot is provided with a discharge outlet 24.

[0072] The inner wall of the slot has four inlets; the outer wall of the slot has four outlets. There are three sets of interlocking slots and dispersing teeth. Each set of dispersing teeth has 25 teeth, each 2cm long and 1.5mm thick. The slot is 1.7mm wide and 2.2cm deep. The inlet or outlet is 2mm wide.

[0073] The anti-back-mixing high-speed dispersion tube includes the following components: tube, anti-back-mixing high-speed dispersion device, flat-plate sawtooth dispersion disc 22, tube bottom inlet 13, tube top outlet 19, tube wall inlet, and drive shaft; wherein, the cap-type dispersion turntable is fixed on the drive shaft, the dispersion stator is fixed on the inner wall of the tube, the tube wall inlet is located at the lower part of the anti-back-mixing high-speed dispersion device, and the dispersion disc 22 is located at the lower part of the anti-back-mixing high-speed dispersion device.

[0074] Table 1. Raw material ratios for the synthesis of hydroxyacrylic acid dispersion

[0075]

[0076]

[0077] Example 2

[0078] The continuous production process of aqueous hydroxyacrylic acid dispersion using the apparatus of Example 1 includes the following steps: According to the formulation in Table 1,

[0079] 1) The temperature of the first-stage monomer continuous polymerization reactor 2 is raised to 140℃. Butyl acrylate (BA), butyl methacrylate (BMA), methyl methacrylate (MMA), hydroxypropyl acrylate (HPA), styrene (ST), hydroxyethyl methacrylate (HEMA), and ethylene glycol butyl ether (BCS) are added to the first-stage monomer feed tank 1 in proportion. The initiator di-tert-amyl peroxide (DTAP) is added to the initiator feed tank 7, and then added dropwise to the first-stage monomer continuous polymerization reactor 2 at a rate of 371 g / min. Simultaneously, the initiator is added dropwise to the first-stage monomer continuous polymerization reactor 2 at a rate of 14 g / min. The polymerization reactor is stirred and maintained at 150 rpm, and the temperature is maintained at 138-142℃ for 5 hours. Then, methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), and butyl acrylate (BA) are added to the second-stage monomer feed tank 4 in proportion.

[0080] 2) After 5 hours of reaction in the first-stage continuous polymerization reactor 2, the prepolymer is transferred to the second-stage continuous polymerization reactor 5 at a transfer rate of 385 g / min. Simultaneously, the second-stage monomer and initiator are added dropwise to the second-stage continuous polymerization reactor 5 at a drop rate of 119.5 g / min and 3.5 g / min, respectively. The rotation speed of the second-stage continuous polymerization reactor 5 is 150 rpm, the temperature is maintained at 138-142℃, and the reaction residence time is 90 min. Then, it is transferred to the post-treatment tubular reactor 9 with static mixing at a transfer flow rate of 508 g / min. After 1 hour of residence... The material enters the cooling pipe 10 with static mixing, where it is cooled to below 120°C. Then, it enters the bottom inlet 13 of the anti-back-mixing high-speed dispersion pipe 11. First, the hydroxypropyl prepolymer is premixed with 20% of the total dispersion water through the first-stage anti-back-mixing high-speed dispersion device, which lowers the temperature of the prepolymer to below 120°C and reduces its viscosity. After premixing, a neutralizing agent is added to the prepolymer in the first chamber. The neutralized prepolymer is then mixed through the second-stage anti-back-mixing high-speed dispersion device and enters the second chamber to be mixed and dispersed with the dispersion water. After being dispersed through the third-stage anti-back-mixing high-speed dispersion device, a qualified dispersion is formed and enters the finished product storage tank.

[0081] During continuous production, samples were taken for testing at intervals of 30 min, 1 h, and 3 h. The results of measuring particle size, fineness, and slag content of the three samples are shown in Table 3.

[0082] Table 2. Raw material ratios for the synthesis of hydroxyacrylic acid dispersions

[0083]

[0084]

[0085] Example 3

[0086] The continuous production process of aqueous hydroxyacrylic acid dispersion using the apparatus of Example 1 includes the following steps: According to the formulation in Table 2,

[0087] 1) Add n-butyl acrylate (BA), butyl methacrylate (BMA), methyl methacrylate (MMA), hydroxypropyl acrylate (HPA), styrene (ST), hydroxyethyl methacrylate (HEMA), and ethylene glycol butyl ether (BCS) to the first-stage monomer feed tank 1 in proportion, and add methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), and acrylic acid (AA) to the second-stage monomer feed tank 4 in proportion.

[0088] 2) Heat the first-stage monomer continuous polymerization reactor 2 to 140℃, add the initiator di-tert-amyl peroxide (DTAP) into the initiator feed tank 7, and then add it dropwise to the first-stage monomer continuous polymerization reactor 2 at a dropping rate of 421 g / min. At the same time, add the initiator dropwise to the first-stage monomer continuous polymerization reactor 2 at a dropping rate of 12.5 g / min. Start the stirring in the polymerization reactor and maintain it at 150 rpm. Maintain the temperature at 138-142℃ for 5 hours. After 5 hours of reaction in the first-stage continuous polymerization reactor 2, the prepolymer is transferred to the second-stage continuous polymerization reactor 5 at a transfer rate of 433.5 g / min. Simultaneously, the second-stage monomer and initiator are added dropwise to the second-stage reactor 5 at a drop rate of 118 g / min and 3.5 g / min, respectively. The second-stage continuous polymerization reactor is rotated at 150 rpm and maintained at a temperature of 138-142℃ for a residence time of 90 minutes. Then, the prepolymer is transferred to a post-treatment tubular reactor 9 with static mixing at a flow rate of 551.85 g / min, and after a residence time of 1 hour... The material enters the cooling pipe 10 with static mixing, where it is cooled to below 120°C. Then, it enters the bottom inlet 13 of the anti-back-mixing high-speed dispersion pipe 11. First, the hydroxypropyl prepolymer is premixed with 20% of the total water volume through the first-stage anti-back-mixing high-speed dispersion device, which lowers the temperature of the prepolymer to below 100°C and reduces its viscosity. After premixing, a neutralizing agent is added to the prepolymer in the first chamber. The neutralized prepolymer is then mixed through the second-stage anti-back-mixing high-speed dispersion device and enters the second chamber to be mixed and dispersed with the dispersion water. After being dispersed through the third-stage anti-back-mixing high-speed dispersion device, a qualified dispersion is formed and enters the finished product storage tank.

[0089] During continuous production, samples were taken for testing at intervals of 30 min, 1 h, and 3 h. The results of measuring particle size, fineness, and slag content of the three samples are shown in Table 3.

[0090] Comparative Example 1

[0091] The apparatus of Example 1 is used, wherein the anti-backmixing high-speed dispersion tube 11 is replaced by a pipeline high-speed continuous neutralization pump and a pipeline high-speed dispersion pump, while other equipment remains unchanged. The continuous production process of the aqueous hydroxyacrylic acid dispersion includes the following steps: according to the formulation in Table 1.

[0092] 1) Add n-butyl acrylate (BA), butyl methacrylate (BMA), methyl methacrylate (MMA), hydroxypropyl acrylate (HPA), styrene (ST), hydroxyethyl methacrylate (HEMA), and ethylene glycol butyl ether (BCS) to the first-stage monomer feed tank 1 in proportion, and add methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), and acrylic acid (AA) to the second-stage monomer feed tank 4 in proportion.

[0093] 2) Heat the first-stage monomer continuous polymerization reactor 2 to 140℃, add the initiator di-tert-amyl peroxide (DTAP) into the initiator feed tank 7, and then drop it into the first-stage monomer continuous polymerization reactor 2 at a dropping rate of 371 g / min. At the same time, add the initiator drop into the first-stage monomer continuous polymerization reactor 2 at a dropping rate of 14 g / min. Start the stirring in the polymerization reactor and maintain it at 150 rpm. Maintain the temperature at 138-142℃ for 5 hours. After 5 hours of reaction in the first-stage continuous polymerization reactor 2, the prepolymer is transferred to the second-stage continuous polymerization reactor 5 at a transfer rate of 385 g / min. Simultaneously, the second-stage monomer and initiator are added dropwise to the second-stage reactor 5 at a drop rate of 119.5 g / min and 3.5 g / min, respectively. The second-stage reactor rotates at 150 rpm and maintains a temperature of 138-142℃ for a residence time of 90 minutes. The prepolymer is then transferred to a post-treatment tubular reactor 9 with static mixing at a flow rate of 508 g / min. After a 1-hour residence time, it enters a cooling pipe 10 with static mixing, where it is cooled to below 120℃. It then enters a pipeline high-speed continuous neutralization pump for neutralization with a neutralizing agent. After neutralization, it enters a pipeline high-speed dispersion pump for mixing and dispersion with dispersion water. The resulting dispersion enters the finished product storage tank.

[0094] During continuous production, samples were taken for testing at intervals of 30 min, 1 h, and 3 h. The results of measuring particle size, fineness, and slag content of the three samples are shown in Table 3.

[0095] Comparative Example 2

[0096] The aqueous batch production of hydroxyacrylic acid dispersions uses a batch production unit (model KLQB) manufactured by Koly, which consists of a polymerization reactor, an oil bath heating system, and a dispersion reactor.

[0097] The method for batch production of aqueous hydroxyacrylic acid dispersions is as follows:

[0098] 1) Prepare the monomers according to the raw material ratio in Table 2.

[0099] 2) Add the base solvent BCS to the polymerization reactor, heat the reactor to 140°C, then add the base initiator DTAP and maintain the temperature for 15 minutes.

[0100] 3) Monomer is added dropwise to the polymerization reactor through monomer tank 1, while initiator is added dropwise simultaneously. The temperature is maintained at 140℃. The dropwise addition rate of the first-stage monomer is 311 g / min, and the dropwise addition rate of the first-stage initiator is 12.5 g / min. After 5 hours of dropwise addition, the temperature is maintained for 15 minutes. Then, the second-stage monomer and the second-stage initiator are added dropwise to the polymerization reactor. The dropwise addition rate of the second-stage monomer is 311 g / min, and the dropwise addition rate of the initiator is 12.5 g / min. After 1.5 hours of dropwise addition, the temperature is lowered to 120℃, and then the mixture is transferred to a dispersion tank. A neutralizing agent is added and stirred for 5 minutes. Then, dispersing water is added to disperse the mixture, resulting in a qualified dispersion.

[0101] After dispersion, three samples were taken to measure particle size, viscosity, slag content and fineness. The results are shown in Table 3.

[0102] Table 3 Comparison of test results between the examples and comparative samples

[0103]

[0104] The coatings were prepared according to the formula in Table 4, and their performance was evaluated. The results are shown in Table 5.

[0105] Table 4 Coating Formulation

[0106] Raw material name wt% Examples or comparative dispersions 45 water 16.4 Nami White Pulp 33.4 DMEA 0.1 Tego4100 0.3 BYK011 0.3 BCS 2 DPNB 2 Glide100 0.2 BYK425, 50% 0.3

[0107] Table 5 Coating Evaluation Results

[0108] Example 2 Example 3 Comparative Example 1 Comparative Example 2 1D Steering Rod Stiffness 35 32 33 30 2D 43 41 41 40 4D 55 50 50 48 Solvent content 3％ 11％ 3％ 11％ Transparency ★★★★ ★★★☆ ★★★☆ ★★★ luster 74 / 89 72 / 87 73 / 86 70 / 85

[0109] Based on the results of Examples 2 and 3 and Comparative Examples 1 and 2 in Tables 3 and 5, the formulations of Examples 2 and 3 are different. Example 2 is a low-solvent formulation, while Example 3 is a high-solvent formulation. Comparing the continuous production process of Example 3 with the batch production process of Comparative Example 2, the results of slag content, fineness, particle size, and performance evaluation show that the low-solvent formulation outperforms the high-solvent formulation in all aspects, and the continuous production process is superior to the batch production process. A comparison of Example 2 and Comparative Example 1 shows that the continuous process using an anti-backmixing high-speed dispersion device and dispersion tube is better than the continuous process using a high-speed mixing pump in terms of slag content, fineness, particle size, and performance evaluation.

[0110] Comparing the results of Example 2 with Comparative Examples 1 and 2 in Table 3, the residue content, fineness, and particle size of the finished product in Comparative Example 1, which resulted from changing the neutralization and dispersion methods, were significantly higher than those in Example 2 and Comparative Example 2. The results did not meet expectations.

[0111] Specifically, the production of 240 kg of aqueous hydroxypropyl dispersion was used as the benchmark for comparison. Since the batch production process involves adding 240 kg of raw material to the polymerization reactor in a single drop, the entire process takes approximately 14 hours to produce the product. Therefore, the average yield per hour is 17.19 kg. The production efficiencies of the continuous process in Example 2 and the batch process in Comparative Example 1 are shown in Table 6.

[0112] Table 6 Production efficiency of Example 2 continuous process and Comparative Example 1 batch process

[0113] Production process Average hourly production (KG) Production time (H) Total production (KG) Continuous production 60 4 240 Intermittent production 17.19 14 240

[0114] A comparison of the data in Table 6 reveals that, under the same production conditions, continuous production is 3.5 times more efficient than intermittent production. During long-term operation, continuous production consumes 50% less energy and liquid than intermittent production because it eliminates the need for kettle washing and temperature adjustments. Furthermore, continuous production avoids the need for a pre-solvent, allowing for a solvent content as low as 3%, while intermittent production requires a higher solvent content. Therefore, continuously produced waterborne hydroxyacrylic acid dispersions have lower VOCs and are more environmentally friendly.

[0115] The prepolymer is gradually cooled, neutralized and dispersed in the anti-back-mixing high-speed dispersion tube 11. Each cavity has an anti-back-mixing high-speed dispersion device, so there is no back-mixing phenomenon, achieving the effect of flat flow. This makes the residence time of the material in each cavity relatively uniform, and the quality of the finished product is stable.

[0116] The process and apparatus for continuous production of waterborne low-solvent hydroxy acrylic resin of the present invention achieve stable and efficient operation, reduce the energy consumption of intermittent production equipment, improve production efficiency, reduce the demand for a large amount of cleaning solvent, solve the problem of inconsistent quality between product batches, and can be applied and promoted to all production requirements of waterborne hydroxy acrylic resin, with broad application prospects.

[0117] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A high-speed dispersion device for preventing back mixing, comprising the following components: a dispersion stator (17) and a cap-type dispersion turntable (18), wherein the upper part of the dispersion stator is provided with a slot and the lower part of the cap-type dispersion turntable is provided with dispersion teeth, the slot and the dispersion teeth meshing; the inner wall of the slot is provided with a feed inlet (23) and the outer wall of the slot is provided with a discharge outlet (24).

2. The anti-back-mixing high-speed dispersion device according to claim 1, characterized in that, The inner wall of the card slot is provided with 3-5 inlet ports; the outer wall of the card slot is provided with 3-5 outlet ports; and / or, the interlocking card slots and dispersing teeth are 1 set, 2 sets, 3 sets, 4 sets or more.

3. The anti-back-mixing high-speed dispersion device according to claim 2, characterized in that, The number of dispersing teeth in a set is 15-30; the length of the dispersing teeth is 1-3cm, and the thickness of the dispersing teeth is 0.7-2mm; the width of the slot is 1-3mm, and the depth is 1-3.5cm; the width of the feed inlet or discharge outlet is 1-2.5mm.

4. The anti-back-mixing high-speed dispersion device according to claim 3, characterized in that, The number of dispersion teeth in one set is 18-25.

5. A high-speed dispersion tube for preventing back-mixing, comprising the following components: a tube, a high-speed dispersion device for preventing back-mixing as described in any one of claims 1-4, a flat-plate sawtooth dispersion disc (22), a bottom inlet (13), a top outlet (19), a wall inlet, and a drive shaft; wherein, The cap-type dispersing turntable is fixed on the drive shaft, the dispersing stator is fixed on the inner wall of the tube, the tube wall feed port is set at the lower part of the anti-back-mixing high-speed dispersing device, and the flat plate sawtooth dispersing disc (22) is set at the lower part of the anti-back-mixing high-speed dispersing device.

6. The anti-back-mixing high-speed dispersion tube according to claim 5, characterized in that, The anti-back-mixing high-speed dispersion device is configured with 2-5 stages; there is a cavity between adjacent stages of the anti-back-mixing high-speed dispersion device.

7. The anti-back-mixing high-speed dispersion tube according to claim 6, characterized in that, The first-level anti-back-mixing high-speed dispersion device located at the bottom of the anti-back-mixing high-speed dispersion tube does not have a flat-plate sawtooth dispersion disc (22).

8. A continuous production apparatus for an aqueous hydroxyacrylic acid dispersion, comprising the following components: a hydroxypropyl first-stage monomer feed tank (1), a first-stage monomer continuous polymerization reactor (2), an initiator feed tank (3), a second-stage monomer feed tank (4), a second-stage monomer continuous polymerization reactor (5), a viscosity-reducing water feed tank (6), a neutralizing agent feed tank (7), a dispersion water feed tank (8), a post-treatment tubular reactor with static mixing (9), a cooling pipe with static mixing (10), a back-mixing prevention high-speed dispersion pipe (11) as described in any one of claims 5-7, and a finished product storage tank (12), wherein the back-mixing prevention high-speed dispersion pipe (11) is provided with a 3-stage back-mixing prevention high-speed dispersion device from bottom to top; wherein, The bottom outlet of the hydroxypropyl first-stage monomer feed tank (1) is connected to the first-stage monomer continuous polymerization reactor (2). The bottom outlet of the initiator feed tank (3) is connected to the first-stage monomer continuous polymerization reactor (2) and the second-stage monomer continuous polymerization reactor (5) respectively. The bottom outlet of the second-stage monomer feed tank (4) is connected to the second-stage monomer continuous polymerization reactor (5). The bottom outlet of the first-stage monomer continuous polymerization reactor (2) is connected to the upper inlet of the second-stage monomer continuous polymerization reactor (5). The bottom outlet of the second-stage monomer continuous polymerization reactor (5) is connected to the post-treatment tubular reactor (9) with static mixing. ), then connected to the cooling pipe (10) with static mixing, then connected to the bottom inlet (13) of the anti-backmixing high-speed dispersion pipe (11), and the top outlet (19) connected to the finished product storage tank (12); the viscosity reducing water inlet tank (6) is connected to the viscosity reducing water pipe wall inlet (14) of the anti-backmixing high-speed dispersion pipe (11), the neutralizing agent inlet tank (7) is connected to the neutralizing agent pipe wall inlet (15) of the anti-backmixing high-speed dispersion pipe (11), and the dispersion water inlet tank (8) is connected to the dispersion water pipe wall inlet (16) of the anti-backmixing high-speed dispersion pipe (11).

9. A process for preparing an aqueous hydroxyacrylic acid dispersion, the process employing the continuous production apparatus for the aqueous hydroxyacrylic acid dispersion as described in claim 8, comprising the following steps: 1) The temperature of the first-stage monomer continuous polymerization reactor (2) is raised to 138-142℃, the stirring is turned on and the speed is kept at 140-160 rpm. Then the reaction is continuously added through the hydroxypropyl first-stage monomer feed tank (1). The residence time of the monomer in the reactor is 4.5-5.5h. 2) The temperature of the two-stage monomer continuous polymerization reactor (5) is raised to 138-142℃. The prepolymer from the one-stage monomer continuous polymerization reactor (2) enters the two-stage monomer continuous polymerization reactor (5). At the same time, the two-stage monomer is added dropwise from the two-stage monomer feed tank (4) to the two-stage monomer continuous polymerization reactor (5). Stirring is started at the same time, and the temperature is maintained at 138-142℃. The average residence time of the prepolymer is 1-2 hours. The stirring speed is 140-160 rpm. 3) The product from the two-stage monomer continuous polymerization reactor enters the post-treatment tubular reactor (9) with static mixing, where it stays for 1-1.5 hours and the temperature is maintained at 138-142℃; 4) The product from step 3) enters the cooling tube (10) with static mixing and is cooled to 110-120℃; then it enters the bottom feed port (13) of the anti-back-mixing high-speed dispersion tube (11), the viscosity reducing water enters the viscosity reducing water tube wall feed port (14) of the anti-back-mixing high-speed dispersion tube (11), the neutralizing agent enters the neutralizing agent tube wall feed port (15) of the anti-back-mixing high-speed dispersion tube (11), and the dispersion water enters the dispersion water tube wall feed port (16) of the anti-back-mixing high-speed dispersion tube (11).

10. The process according to claim 9, characterized in that, The monomer in the hydroxypropyl monomer feed tank (1) contains one or more of the following: n-butyl acrylate, butyl methacrylate, methyl methacrylate, hydroxypropyl acrylate, styrene, hydroxyethyl methacrylate, and ethylene glycol butyl ether.

11. The process according to claim 9, characterized in that, The monomers in the two-stage monomer feed tank (4) include one or more of butyl methacrylate, hydroxyethyl methacrylate, n-butyl acrylate, and acrylic acid.

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