A flaky polycarboxylic acid water reducing agent and a method for manufacturing the same

Abstract

This invention relates to a sheet-like polycarboxylate superplasticizer, whose macromonomer is ethylene glycol monovinyl polyethylene glycol ether (EPEG) and minor monomer is acrylic acid. The polycarboxylate superplasticizer is in the form of dried tablets and is soluble in water. The method for producing this sheet-like polycarboxylate superplasticizer involves using a high-concentration monomer direct copolymerization reaction to produce a polycarboxylate superplasticizer with a concentration greater than 60%; concentrating the polycarboxylate superplasticizer with a concentration greater than 60% to a concentration greater than 85% using a negative pressure concentration method; and drying the polycarboxylate superplasticizer with a concentration greater than 85% using a room-temperature flat-laying strong exhaust method to form thin sheets, which are then cut into flakes. The beneficial technical effects of this invention's sheet-like polycarboxylate superplasticizer and its production method are that the weight and volume of the polycarboxylate superplasticizer are only 1 / 4 to 1 / 5 of the liquid product, greatly reducing logistics and storage costs; it does not freeze or degrade, exhibiting strong stability; and it is flexible in use and allows for precise compounding.

Description

Technical Field

[0001] This invention relates to the manufacturing technology of polycarboxylate superplasticizers, and particularly to a sheet-like polycarboxylate superplasticizer and its manufacturing method. Background Technology

[0002] Polycarboxylate superplasticizer, as an additive for high-performance concrete, has been widely used in high-speed rail, hydropower, nuclear power, highways, municipal infrastructure construction and civil buildings. Compared with traditional superplasticizers (such as naphthalene-based, aliphatic, aminosulfonate-based, etc.), it has the following technical advantages: (1) Low dosage and high water reduction rate. The dosage of polycarboxylate superplasticizer is usually only 0.1% to 0.3% of the mass of cementitious materials, which can achieve a significant water reduction rate of more than 30%, thereby greatly reducing the water-cement ratio and improving the strength and durability of concrete. (2) Excellent slump retention performance. The carboxylic acid groups in its molecular structure can delay the cement hydration process and effectively control the slump loss of concrete. The slump retention rate is more than 93% after 1 hour. It can still maintain good fluidity in high temperature environment, which is conducive to long-distance transportation and complex construction operations. (3) It is environmentally friendly and safe. It does not contain toxic substances such as formaldehyde and naphthalene during production and use. The chloride ion and alkali content is extremely low (e.g., alkali content ≤ 0.2%), which meets the green building material standards. It is environmentally friendly and helps to improve the durability of concrete. (4) It enhances the comprehensive performance of concrete. Adding polycarboxylate superplasticizer can significantly improve the early strength (more than 50%) and 28-day strength (more than 30%) of concrete. At the same time, the shrinkage rate is small, which can improve the volume stability of concrete and reduce the risk of cracking. (5) It has strong economic benefits and practicality. Due to the low dosage and high water reduction rate, the amount of cement can be reduced and the proportion of mineral admixtures can be increased, thereby reducing the overall project cost. At the same time, polycarboxylate superplasticizer also has the advantages of good product stability and no precipitation at low temperature.

[0003] However, most polycarboxylate superplasticizers on the market are currently liquid, with a small portion being powdered polycarboxylate superplasticizers used in dry-mixed mortars. Liquid polycarboxylate superplasticizers are wasteful due to high transportation and storage costs, short shelf life, and freezing, delamination, and deterioration in winter. Powdered polycarboxylate superplasticizers are dried in spray drying towers, and the molecular structure of polycarboxylate superplasticizers undergoes cross-linking polymerization during the high-temperature drying process. The properties of the dried polycarboxylate superplasticizer powder have changed, and its water reduction rate and slump retention may both deteriorate. Summary of the Invention

[0004] To address the above problems, this invention proposes a sheet-like polycarboxylate superplasticizer and its preparation method.

[0005] The present invention relates to a sheet-like polycarboxylate superplasticizer, wherein the macromonomer is ethylene glycol monovinyl polyethylene glycol ether (EPEG) and the minor monomer is acrylic acid; the polycarboxylate superplasticizer is in the form of a dry tablet, and the sheet-like polycarboxylate superplasticizer is soluble in water.

[0006] The present invention discloses a method for producing sheet-like polycarboxylate superplasticizer, which involves using a high-concentration monomer direct copolymerization reaction to produce a polycarboxylate superplasticizer with a concentration greater than 60%; using a negative pressure concentration method to concentrate the polycarboxylate superplasticizer with a concentration greater than 60% to a concentration greater than 85%; and using a room temperature flat-laying strong exhaust method to dry the polycarboxylate superplasticizer with a concentration greater than 85% to form thin sheets, which are then cut into sheet shapes.

[0007] Furthermore, the method of producing a polycarboxylate superplasticizer with a concentration greater than 60% using a high-concentration monomer direct copolymerization reaction includes the following steps:

[0008] S1. Ethylene glycol monovinyl polyethylene glycol ether (EPEG) is used as the macromonomer, acrylic acid as the micromonomer, H₂O₂ as the oxidizing component, vitamin C as the reducing component, sodium hypophosphite as the chain transfer agent, and a 1% ferrous sulfate heptahydrate solution as the catalytic component. The ratio is: EPEG : acrylic acid : H₂O₂ : vitamin C : sodium hypophosphite : 1% ferrous sulfate heptahydrate solution = 10–13 : 0.5–2 : 0.06–0.12 : 0.11–0.18 : 0.015–0.021 : 0.005–0.009. Weigh each component according to the ratio and set aside.

[0009] S2. Add the weighed EPEG and deionized water to a stirred reactor, stir to dissolve, and prepare a 60% polyether monomer solution for later use.

[0010] S3. Prepare an 85% solution A by mixing the weighed acrylic acid and deionized water.

[0011] S4. Prepare a 10% solution B by weighing out vitamin C, 1% ferrous sulfate heptahydrate solution and deionized water, and set aside.

[0012] S5. At a temperature of 20±5℃, add 0.15% sodium hypophosphite (by mass of EPEG) to a reactor containing a 60% polyether monomer solution and stir for 2-5 minutes. Then add 0.75% hydrogen peroxide (by mass of EPEG) and stir for another 2-5 minutes.

[0013] S6. Using a peristaltic pump, solution A and solution B are simultaneously added dropwise at a uniform rate to a reactor containing a 60% concentration of polyether monomer solution. Solution A is added dropwise at a uniform rate over 50 minutes, and solution B is added dropwise at a uniform rate over 55 minutes.

[0014] S7. After the addition is complete, control the temperature at 38-42℃ and stir for 1 hour. The reaction ends at 40-45℃ to obtain a polycarboxylate superplasticizer with a concentration of over 60%.

[0015] Furthermore, the method of concentrating polycarboxylate superplasticizer with a concentration greater than 60% to a concentration greater than 85% using negative pressure concentration includes the following steps:

[0016] S8. Slowly heat the reactor containing a 60% polyether monomer solution to 70-80°C with stirring. At the same time, turn on the vacuum pump to evacuate the reactor to a vacuum level of -0.06MPa to -0.09MPa.

[0017] S9. Stir continuously for 1.5h to 2h under vacuum negative pressure;

[0018] S10. Slowly adjust to room temperature and pressure under stirring to obtain a polycarboxylate superplasticizer with a concentration greater than 85%.

[0019] Furthermore, the method of drying polycarboxylate superplasticizer with a concentration greater than 85% into thin sheets and slicing them using a room temperature flat-laying forced exhaust method includes using a steel strip sheeter to dry and slice the polycarboxylate superplasticizer with a concentration greater than 85%; the steel strip sheeter includes: a feeding hopper, a conveyor steel belt, a fan, and a scraping mechanism; the feeding hopper includes an inverted trapezoidal hopper body, a discharge hole, and a scraper; the inverted trapezoidal hopper body is fixed to the end of the conveyor steel belt, the discharge holes are evenly distributed laterally at the bottom of the inverted trapezoidal hopper body, and the scraper is fixed to the bottom front side of the feeding hopper; the front end of the conveyor steel belt is installed directly below the front side of the feeding hopper, and a vibration device is provided at the front end of the conveyor steel belt; multiple fans are fixed longitudinally along the conveyor steel belt at intervals on a U-shaped fixing frame spanning the conveyor steel belt; the scraping mechanism is fixed to the end of the conveyor steel belt; and includes the following steps:

[0020] S11. Inject the polycarboxylate superplasticizer with a concentration greater than 85% concentrated under negative pressure into the fabric hopper;

[0021] S12. The polycarboxylate superplasticizer in the hopper is spread evenly on the steel belt through the discharge hole at a speed of 5-12 L / min. That is, by adjusting the discharge speed, the distance between the scraper and the conveyor steel belt and the vibration intensity of the vibration device, the polycarboxylate superplasticizer is evenly spread on the steel belt with a thickness of 0.8-2 mm.

[0022] S13. Turn on the blower, and the blower will blow strong air in the opposite direction to the molten material on the steel belt;

[0023] S14. As the conveyor belt moves forward, the polycarboxylate superplasticizer spread on the belt cools and agglomerates, then dries to form thin sheets.

[0024] S15. The scraper mechanism located at the end of the conveyor belt scrapes off the thin sheet of polycarboxylate superplasticizer and breaks it into the receiving frame.

[0025] Furthermore, the scraping mechanism includes: a feeding seat 4-1, a feeding plate 4-2, and a scraping mechanism 4-3; the feeding seat is fixed in front of the conveyor steel belt, and a rotating shaft with its axis parallel to the axis of the conveyor steel belt roller is provided in the middle of the feeding seat; the feeding plate is inclined and fixed on the rotating shaft of the feeding seat, and the front end of the feeding plate faces the outer surface of the end roller section of the conveyor steel belt; the scraping mechanism is fixed on the rear side of the feeding plate, and its cross-shaped scraping wheel is provided at the end of the feeding plate.

[0026] Furthermore, the ratio of each component in step S1 is: EPEG∶acrylic acid∶H2O2∶vitamin C∶sodium hypophosphite∶1% ferrous sulfate heptahydrate solution = 12∶1∶0.09∶0.14∶0.018∶0.007.

[0027] Furthermore, the conveyor belt is 30 meters long, 1.5 meters wide, and moves forward at a rate of 0.05 meters per second.

[0028] Furthermore, the installation spacing of the fans is no more than 3 meters, and the flow rate of the fans is 9000-12000 m3 / h.

[0029] The beneficial technical effects of the sheet-like polycarboxylate superplasticizer and its manufacturing method of the present invention are that the polycarboxylate superplasticizer is made into tablets, whose weight and volume are only 1 / 4 to 1 / 5 of the liquid product, which greatly reduces logistics and storage costs; it does not freeze or become ineffective and has strong stability; and it is flexible in use and can be precisely compounded. Attached Figure Description

[0030] Appendix Figure 1 This is a schematic diagram of the steel strip slagging machine of the present invention;

[0031] Appendix Figure 2 This is a schematic diagram of the structure of the feeding hopper of the steel strip slab forming machine of the present invention.

[0032] Appendix Figure 3 This is a schematic diagram of the scraper mechanism of the present invention.

[0033] In the diagram, 1 is the material hopper, 1-1 is the inverted trapezoidal hopper body, 1-2 is the discharge hole, and 1-3 is the scraper; 2 is the conveyor belt, 3 is the fan, 4 is the scraper mechanism, 4-1 is the feeding seat, 4-2 is the feeding plate, and 4-3 is the scraping mechanism.

[0034] The flake polycarboxylate superplasticizer and its preparation method of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0035] The present invention relates to a sheet-like polycarboxylate superplasticizer, wherein the macromonomer is ethylene glycol monovinyl polyethylene glycol ether (EPEG) and the minor monomer is acrylic acid; the polycarboxylate superplasticizer is in the form of a dry tablet, and the sheet-like polycarboxylate superplasticizer is soluble in water.

[0036] This invention discloses a method for producing sheet-like polycarboxylate superplasticizer. The method involves using a high-concentration monomer direct copolymerization reaction to prepare a polycarboxylate superplasticizer with a concentration greater than 60%; concentrating the polycarboxylate superplasticizer to a concentration greater than 85% using a negative pressure concentration method; and finally drying the polycarboxylate superplasticizer to a concentration greater than 85% using a room-temperature, flat-lay, and strongly exhaust method to form thin sheets, which are then cut into tablets. The method further involves preparing a polycarboxylate superplasticizer with a concentration greater than 60% using a high-concentration monomer direct copolymerization method, then further increasing the concentration of the polycarboxylate superplasticizer to over 85% using a negative pressure concentration method, and finally completely drying the polycarboxylate superplasticizer to form tablets using a room-temperature, flat-lay, and strongly exhaust method. Because the overall concentration was controlled during the direct copolymerization reaction of the monomers, the concentration of the polycarboxylate superplasticizer was greater than 60%. The negative pressure concentration method not only further increased the concentration of the polycarboxylate superplasticizer to over 85%, but also ensured that the structure and composition of the polycarboxylate superplasticizer were not damaged, thus guaranteeing that its performance was not affected. The subsequent room-temperature flat-laying and forced-air ventilation method is a physical drying method and will not affect the performance of the polycarboxylate superplasticizer in any way. Clearly, the effective and organic integration of these three processes enables the preparation of dry, sheet-like polycarboxylate superplasticizer while ensuring that its performance is not affected, and the sheet-like polycarboxylate superplasticizer is soluble in water.

[0037] As one of the preferred technical solutions, the method of producing a polycarboxylate superplasticizer with a concentration greater than 60% using a high-concentration monomer direct copolymerization reaction includes the following steps:

[0038] S1. Ethylene glycol monovinyl polyethylene glycol ether (EPEG) is used as the macromonomer, acrylic acid as the micromonomer, H₂O₂ as the oxidizing component, vitamin C as the reducing component, sodium hypophosphite as the chain transfer agent, and a 1% ferrous sulfate heptahydrate solution as the catalytic component. The ratio is: EPEG : acrylic acid : H₂O₂ : vitamin C : sodium hypophosphite : 1% ferrous sulfate heptahydrate solution = 10–13 : 0.5–2 : 0.06–0.12 : 0.11–0.18 : 0.015–0.021 : 0.005–0.009. Weigh each component according to the ratio and set aside.

[0039] S2. Add the weighed EPEG and deionized water to a stirred reactor, stir to dissolve, and prepare a 60% polyether monomer solution for later use.

[0040] S3. Prepare an 85% solution A by mixing the weighed acrylic acid and deionized water.

[0041] S4. Prepare a 10% solution B by weighing out vitamin C, 1% ferrous sulfate heptahydrate solution and deionized water, and set aside.

[0042] S5. At a temperature of 20±5℃, add 0.15% sodium hypophosphite (by mass of EPEG) to a reactor containing a 60% polyether monomer solution and stir for 2-5 minutes. Then add 0.75% hydrogen peroxide (by mass of EPEG) and stir for another 2-5 minutes.

[0043] S6. Using a peristaltic pump, solution A and solution B are simultaneously added dropwise at a uniform rate to a reactor containing a 60% concentration of polyether monomer solution. Solution A is added dropwise at a uniform rate over 50 minutes, and solution B is added dropwise at a uniform rate over 55 minutes.

[0044] S7. After the addition is complete, control the temperature at 38-42℃ and stir for 1 hour. The reaction ends at 40-45℃ to obtain a polycarboxylate superplasticizer with a concentration of over 60%.

[0045] As one of the preferred technical solutions, the method of concentrating a polycarboxylate superplasticizer with a concentration greater than 60% to a concentration greater than 85% using a negative pressure concentration method includes the following steps:

[0046] S8. Slowly heat the reactor containing a 60% polyether monomer solution to 70-80°C with stirring. At the same time, turn on the vacuum pump to evacuate the reactor to a vacuum level of -0.06MPa to -0.09MPa.

[0047] S9. Stir continuously for 1.5h to 2h under vacuum negative pressure;

[0048] S10. Slowly adjust to room temperature and pressure under stirring to obtain a polycarboxylate superplasticizer with a concentration greater than 85%.

[0049] See appendix Figure 1 and 2As one of the preferred technical solutions, the method of drying polycarboxylate superplasticizer with a concentration greater than 85% into thin sheets and slicing them using a room temperature flat-laying strong exhaust method includes: using a steel strip sheeter to dry and slice the polycarboxylate superplasticizer with a concentration greater than 85%; the steel strip sheeter includes: a feeding hopper 1, a conveyor steel belt 2, a fan 3, and a scraping mechanism 4; the feeding hopper includes an inverted trapezoidal hopper body 1-1, discharge holes 1-2, and scraper plates 1-3; the inverted trapezoidal hopper body is fixed to the end of the conveyor steel belt, the discharge holes are evenly distributed laterally at the bottom of the inverted trapezoidal hopper body, and the scraper plates are fixed to the bottom front side of the feeding hopper; the front end of the conveyor steel belt is installed directly below the front side of the feeding hopper, and a vibration device is provided at the front end of the conveyor steel belt; multiple fans are fixed longitudinally along the conveyor steel belt on a portal frame spanning the conveyor steel belt; the scraping mechanism is fixed to the end of the conveyor steel belt; and includes the following steps:

[0050] S11. Inject the polycarboxylate superplasticizer with a concentration greater than 85% concentrated under negative pressure into the fabric hopper;

[0051] S12. The polycarboxylate superplasticizer in the hopper is spread evenly on the steel belt through the discharge hole at a speed of 5-12 L / min. That is, by adjusting the discharge speed, the distance between the scraper and the conveyor steel belt and the vibration intensity of the vibration device, the polycarboxylate superplasticizer is evenly spread on the steel belt with a thickness of 0.8-2 mm.

[0052] S13. Turn on the blower, and the blower will blow strong air in the opposite direction to the molten material on the steel belt;

[0053] S14. As the conveyor belt moves forward, the polycarboxylate superplasticizer spread on the belt cools and agglomerates, then dries to form thin sheets.

[0054] S15. The scraper mechanism located at the end of the conveyor belt scrapes off the thin sheet of polycarboxylate superplasticizer and breaks it into the receiving frame.

[0055] Obviously, whether the fluid polycarboxylate superplasticizer can be properly spread evenly on the conveyor belt directly affects the drying effect. This invention employs three measures to ensure that the fluid polycarboxylate superplasticizer is properly spread evenly on the conveyor belt. First, material distribution: controlling the position, uniformity, and flow rate of the fluid polycarboxylate superplasticizer onto the conveyor belt using a material distribution hopper. Second, material scraping: using a scraper to smooth the fluid polycarboxylate superplasticizer flowing onto the conveyor belt and controlling its thickness. Third, vibration: adjusting the amplitude and frequency of the vibration device located at the front end of the conveyor belt further ensures the fluid polycarboxylate superplasticizer is properly spread evenly on the conveyor belt, while simultaneously expelling any gas contained in the fluid polycarboxylate superplasticizer to ensure the quality of the dried sheet polycarboxylate superplasticizer.

[0056] See appendix Figure 3As a preferred technical solution, the scraping mechanism includes: a feeding seat 4-1, a feeding plate 4-2, and a scraping mechanism 4-3; the feeding seat is fixed in front of the conveyor belt, and a rotating shaft with its axis parallel to the axis of the conveyor belt roller is provided in the middle of the feeding seat; the feeding plate is inclinedly fixed on the rotating shaft of the feeding seat, and the front end of the feeding plate faces the outer surface of the end roller section of the conveyor belt; the scraping mechanism is fixed on the rear side of the feeding plate, and its cross-shaped scraping wheel is provided at the end of the feeding plate. By fixing the feeding plate on the rotating shaft of the feeding seat, the tilt angle of the feeding plate is adjusted by rotating the shaft, thereby adjusting the distance between the front end of the feeding plate and the outer surface of the end roller section of the conveyor belt. This ensures that the thin sheet-like polycarboxylate superplasticizer on the conveyor belt can be scraped off by the feeding plate without affecting the normal operation of the conveyor belt or causing any damage to the surface of the conveyor belt. Meanwhile, the cross-shaped shredding rollers located behind the feed plate break the thin sheets of polycarboxylate superplasticizer scraped off the conveyor belt into fragments.

[0057] As one of the preferred technical solutions, the ratio of each component in step S1 is: EPEG∶acrylic acid∶H2O2∶vitamin C∶sodium hypophosphite∶1% ferrous sulfate heptahydrate solution = 12∶1∶0.09∶0.14∶0.018∶0.007.

[0058] As one of the preferred technical solutions, the conveyor belt is 30 meters long, 1.5 meters wide, and moves forward at a rate of 0.05 meters per second. Of course, the length, width, and forward speed of the conveyor belt can be adjusted according to production needs to meet production requirements while ensuring product quality.

[0059] As one of the preferred technical solutions, the installation spacing of the fans is no more than 3 meters, and the fan flow rate is 9000-12000 m³ / h. Of course, the installation spacing and flow rate of the fans can be selected according to actual production needs to meet those needs.

[0060] To verify the performance of the flake polycarboxylate superplasticizer of the present invention, the flake polycarboxylate superplasticizer of the present invention was tested and evaluated according to national standards. The results are shown in the table below:

[0061]

[0062] It is evident that all technical indicators of the sheet-like polycarboxylate superplasticizer of this invention meet the requirements of national standards, and its technical effect fully meets the requirements for use.

[0063] Obviously, the beneficial technical effects of the sheet-like polycarboxylate superplasticizer and its manufacturing method of the present invention are that the polycarboxylate superplasticizer is made into tablets, whose weight and volume are only 1 / 4 to 1 / 5 of the liquid product, which greatly reduces logistics and storage costs; it does not freeze or become ineffective, and has strong stability; and it is flexible in use and can be precisely compounded.

Claims

1. A sheet-like polycarboxylate superplasticizer, characterized in that, The macromonomer of the sheet-like polycarboxylate superplasticizer is ethylene glycol monovinyl polyethylene glycol ether (EPEG), and the micromonomer is acrylic acid; the polycarboxylate superplasticizer is in the form of dry tablets, and the sheet-like polycarboxylate superplasticizer is soluble in water.

2. A method for preparing a sheet-like polycarboxylate superplasticizer, characterized in that, A polycarboxylate superplasticizer with a concentration greater than 60% was prepared by direct copolymerization of high-concentration monomers; the polycarboxylate superplasticizer with a concentration greater than 60% was concentrated to a concentration greater than 85% by negative pressure concentration method; the polycarboxylate superplasticizer with a concentration greater than 85% was dried into thin sheets by room temperature flat laying and strong exhaust method and then cut into slices.

3. The method for preparing the sheet-like polycarboxylate superplasticizer according to claim 2, characterized in that, The method for producing a polycarboxylate superplasticizer with a concentration greater than 60% using a high-concentration monomer direct copolymerization reaction includes the following steps: S1. Ethylene glycol monovinyl polyethylene glycol ether (EPEG) is used as the macromonomer, acrylic acid as the micromonomer, H₂O₂ as the oxidizing component, vitamin C as the reducing component, sodium hypophosphite as the chain transfer agent, and a 1% ferrous sulfate heptahydrate solution as the catalytic component. The ratio is: EPEG : acrylic acid : H₂O₂ : vitamin C : sodium hypophosphite : 1% ferrous sulfate heptahydrate solution = 10–13 : 0.5–2 : 0.06–0.12 : 0.11–0.18 : 0.015–0.021 : 0.005–0.

009. Weigh each component according to the ratio and set aside. S2. Add the weighed EPEG and deionized water to a stirred reactor, stir to dissolve, and prepare a 60% polyether monomer solution for later use. S3. Prepare an 85% solution A by mixing the weighed acrylic acid and deionized water. S4. Prepare a 10% solution B by weighing out vitamin C, 1% ferrous sulfate heptahydrate solution and deionized water, and set aside. S5. At a temperature of 20±5℃, add 0.15% sodium hypophosphite (by mass of EPEG) to a reactor containing a 60% polyether monomer solution and stir for 2-5 minutes. Then add 0.75% hydrogen peroxide (by mass of EPEG) and stir for another 2-5 minutes. S6. Using a peristaltic pump, solution A and solution B are simultaneously added dropwise at a uniform rate to a reactor containing a 60% concentration of polyether monomer solution. Solution A is added dropwise at a uniform rate over 50 minutes, and solution B is added dropwise at a uniform rate over 55 minutes. S7. After the addition is complete, control the temperature at 38-42℃ and stir for 1 hour. The reaction ends at 40-45℃ to obtain a polycarboxylate superplasticizer with a concentration of over 60%.

4. The method for preparing the sheet-like polycarboxylate superplasticizer according to claim 2, characterized in that, The method of concentrating polycarboxylate superplasticizer with a concentration greater than 60% to a concentration greater than 85% using negative pressure concentration includes the following steps: S8. Slowly heat the reactor containing a 60% polyether monomer solution to 70-80°C with stirring. At the same time, turn on the vacuum pump to evacuate the reactor to a vacuum level of -0.06MPa to -0.09MPa. S9. Stir continuously for 1.5h to 2h under vacuum negative pressure; S10. Slowly adjust to room temperature and pressure under stirring to obtain a polycarboxylate superplasticizer with a concentration greater than 85%.

5. The method for preparing the sheet-like polycarboxylate superplasticizer according to claim 2, characterized in that, The method of drying polycarboxylate superplasticizer with a concentration greater than 85% into thin sheets and slicing them using a room-temperature flat-laying and forced-exhaust method includes: using a steel strip sheeter to dry and slice the polycarboxylate superplasticizer with a concentration greater than 85%; the steel strip sheeter includes: a feeding hopper, a conveyor steel belt, a fan, and a scraping mechanism; the feeding hopper includes an inverted trapezoidal hopper body, discharge holes, and a scraper; the inverted trapezoidal hopper body is fixed to the end of the conveyor steel belt, the discharge holes are evenly distributed laterally at the bottom of the inverted trapezoidal hopper body, and the scraper is fixed to the bottom front side of the feeding hopper; the front end of the conveyor steel belt is installed directly below the front side of the feeding hopper, and a vibration device is provided at the front end of the conveyor steel belt; multiple fans are fixed longitudinally along the conveyor steel belt on a U-shaped fixing frame spanning the conveyor steel belt; the scraping mechanism is fixed to the end of the conveyor steel belt; and includes the following steps: S11. Inject the polycarboxylate superplasticizer with a concentration greater than 85% concentrated under negative pressure into the fabric hopper; S12. The polycarboxylate superplasticizer in the hopper is spread evenly on the steel belt through the discharge hole at a speed of 5-12 L / min. That is, by adjusting the discharge speed, the distance between the scraper and the conveyor steel belt and the vibration intensity of the vibration device, the polycarboxylate superplasticizer is evenly spread on the steel belt with a thickness of 0.8-2 mm. S13. Turn on the blower, and the blower will blow strong air in the opposite direction to the molten material on the steel belt; S14. As the conveyor belt moves forward, the polycarboxylate superplasticizer spread on the belt cools and agglomerates, then dries to form thin sheets. S15. The scraper mechanism located at the end of the conveyor belt scrapes off the thin sheet of polycarboxylate superplasticizer and breaks it into the receiving frame.

6. The method for preparing the sheet-like polycarboxylate superplasticizer according to claim 5, characterized in that, The scraping mechanism includes: a feeding seat 4-1, a feeding plate 4-2, and a scraping mechanism 4-3; the feeding seat is fixed in front of the conveyor steel belt, and a rotating shaft with its axis parallel to the axis of the conveyor steel belt roller is provided in the middle of the feeding seat; the feeding plate is inclined and fixed on the rotating shaft of the feeding seat, and the front end of the feeding plate faces the outer surface of the end roller section of the conveyor steel belt; the scraping mechanism is fixed on the rear side of the feeding plate, and its cross-shaped scraping wheel is provided at the end of the feeding plate.

7. The method for preparing the sheet-like polycarboxylate superplasticizer according to claim 3, characterized in that, The ratio of each component in step S1 is: EPEG∶acrylic acid∶H2O2∶vitamin C∶sodium hypophosphite∶1% ferrous sulfate heptahydrate solution = 12∶1∶0.09∶0.14∶0.018∶0.

007.

8. The method for preparing the sheet-like polycarboxylate superplasticizer according to claim 5 or 6, characterized in that, The conveyor belt is 30 meters long, 1.5 meters wide, and moves forward at a rate of 0.05 meters per second.

9. The method for preparing the sheet-like polycarboxylate superplasticizer according to any one of claims 5, 6, and 8, characterized in that, The installation spacing of the fans shall not exceed 3 meters, and the flow rate of the fans shall be 9000-12000 m3 / h.

Images