Preparation method and system of polycarboxylate superplasticizer

Abstract

The invention relates to the technical field of water reducing agents, and discloses a preparation method and system of a polycarboxylic acid water reducing agent. The system comprises a reaction tower, a filtering tower, a recrystallization tower, a distillation tower, a drying tower, an intermediate storage tank, a mixing tower, a cooling tower, a primary product storage tank, a pH adjusting tower, a filtering tower, a high-grade product storage tank, a polycarboxylate superplasticizer storage tank, a raw material storage tank, a feeding equipment box, a waste liquid tank, a solid waste storage device, a water tank and a waste water tank. The system can continuously and stably produce products with consistent and reliable components and performance, and is high in safety performance and good in environmental protection performance. The preparation method of the water reducing agent is realized on the basis of the system, the allyl polyoxyethylene ether is used as a basis, phosphonyl functionalization is introduced, the water absorption is improved, then copolymerization with fumaric acid is carried out, a polymer with a comb-shaped structure is obtained, the structure can provide more adsorption sites, the water reducing performance is excellent, and the water reducing agent has good water reducing performance. The flowability, self-compaction, slump, mechanical strength and durability of the concrete can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of water - reducing agent preparation, and particularly to a preparation method and system for polycarboxylate water - reducing agent. Background Art

[0002] In the modern construction industry, as the core material of buildings, the performance of concrete directly affects the quality and safety of construction projects. With the continuous expansion of the construction scale, higher requirements are put forward for the strength, durability, and construction performance of concrete.

[0003] When traditional water - reducing agents meet these complex and stringent requirements, many limitations gradually emerge. The water - reducing rate of naphthalene - based water - reducing agents is relatively low, the slump retention is poor, and the production process is not very friendly to the environment; although melamine - based water - reducing agents are slightly better in some properties, there are also deficiencies in the water - reducing rate and compatibility with cement. Therefore, polycarboxylate water - reducing agents came into being.

[0004] Chinese Patent with the authorized publication number CN 114516733 B discloses a composite polycarboxylate water - reducing agent. A slow - release water - reducing agent obtained by polymerizing isopentenyl polyoxyethylene ether, acrylic acid, acrylate monomers, and methoxypolyethylene glycol methacrylate, and adding modified attapulgite to obtain a polycarboxylate water - reducing agent with slow - release, good water - reducing property, and mechanical properties. However, modified attapulgite will affect the setting time of concrete, and unreasonable addition amount or poor compounding with polycarboxylate water - reducing agent will, to a certain extent, affect the development of the later - stage strength of concrete. Therefore, it is particularly important to provide a polycarboxylate water - reducing agent with good water - reducing performance, while maintaining the strength of concrete and extending the service life of concrete. Summary of the Invention

[0005] The present invention aims to provide a preparation method and system for polycarboxylate water - reducing agent. The system has a high degree of automation, can accurately measure the ratio of each raw material, continuously and stably produce products with consistent and reliable composition and performance. At the same time, it has high safety performance and good environmental protection performance. The water - reducing agent preparation method is realized based on this system. Based on allyl polyoxyethylene ether, phosphonyl functionalization is introduced to improve water absorption, and then copolymerized with fumaric acid to obtain a comb - shaped polymer. This structure can provide more adsorption sites, has excellent water - reducing performance, and can effectively improve the fluidity, self - compactness, slump, mechanical strength, and durability of concrete.

[0006] To achieve the above object, the present invention provides a preparation system for polycarboxylate water reducer, including a first reaction tower, which is sequentially connected to a first filtration tower, a recrystallization tower, a first distillation tower, a drying tower, an intermediate storage tank, a first mixing tower, a second reaction tower, a cooling tower, a primary product storage tank, a second mixing tower, a pH adjustment tower, a second filtration tower, a second distillation tower, a high-grade product storage tank, a third mixing tower, and a polycarboxylate water reducer storage tank through pipelines; the first reaction tower is also respectively connected to a first raw material storage tank, a second raw material storage tank, an organic solvent storage tank, and a first feeding equipment box; the recrystallization tower is also connected to an ethyl acetate storage tank; the first mixing tower is also respectively connected to a water tank, a third raw material storage tank, and a fourth raw material storage tank; the second reaction tower is also respectively connected to a second feeding equipment box and a third feeding equipment box; the second mixing tower is also connected to a fourth feeding equipment box; the third mixing tower is also connected to a fifth feeding equipment box.

[0007] Preferably, the system further includes a first waste liquid tank, a first solid waste storage, a second waste liquid tank, a second solid waste storage, and a waste water tank; wherein, the first waste liquid tank is connected to the first filtration tower; the first solid waste storage is connected to the recrystallization tower; the second waste liquid tank is respectively connected to the first distillation tower and the drying tower; the second solid waste storage is connected to the second filtration tower; the waste water tank is connected to the second distillation tower.

[0008] Preferably, allyl polyoxyethylene ether is in the first raw material storage tank; acrylic acid phosphate is in the second raw material storage tank; a catalyst is in the first feeding equipment box; deionized water is in the water tank; fumaric acid is in the third raw material storage tank; lignosulfonate is in the fourth raw material storage tank; an initiator solution is in the second feeding equipment box; a chain transfer agent solution is in the third feeding equipment box; a retarder is in the fourth feeding equipment box; a stabilizer is in the fifth feeding equipment box.

[0009] Preferably, waste organic solvent is stored in the first waste liquid tank; waste ethyl acetate is stored in the second waste liquid tank.

[0010] Preferably, mechanical stirring devices, pressure gauges, and thermometers are provided in the first reaction tower, the recrystallization tower, the first mixing tower, the second reaction tower, the cooling tower, the second mixing tower, and the third mixing tower; thermometers and pressure gauges are provided in the first distillation tower, the drying tower, and the second distillation tower; a pH meter is provided in the pH adjustment tower, and the set pH value is 6 - 7; the set temperature of the cooling tower is 30 - 40 °C; valves and flow meters are provided at the inlets and outlets of the pipelines.

[0011] To achieve the above object, the present invention also provides a method for preparing polycarboxylate water reducer based on the above system, including:

[0012] Step S1: Allyl polyoxyethylene ether, acrylic acid phosphate ester and a catalyst are mixed with an organic solvent in a first reaction tower to obtain a crude intermediate product. The crude intermediate product enters a recrystallization tower and is recrystallized with ethyl acetate to obtain an intermediate product.

[0013] Step S2: An initiator and a chain transfer agent are respectively dissolved in deionized water to prepare an initiator solution and a chain transfer agent solution. In a first mixing tower, the intermediate product is mixed with deionized water, heated and stirred for the first time to dissolve, fumaric acid and lignosulfonate are added, and then heated and stirred for the second time to mix evenly to obtain a reaction solution. The reaction solution enters a second reaction tower, and the third heating and stirring starts the reaction. The initiator solution and the chain transfer agent solution are added to the reaction solution in batches within a set time after the start of the reaction to obtain a primary product.

[0014] Step S3: The primary product is mixed with a retarder in a second mixing tower to obtain an intermediate product. The intermediate product is adjusted to a pH of 6 - 7 with an alkali solution in a pH adjustment tower, and then filtered for impurities in a second filtration tower. The filtrate enters a second distillation tower for distillation to obtain a high-grade product. The high-grade product and a stabilizer are stirred and mixed evenly in a third mixing tower to obtain a polycarboxylate water reducer.

[0015] Preferably, in step S1, the organic solvent is any one or more of N,N'-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide.

[0016] Preferably, in step S1, the catalyst is any one or more of potassium tert-butoxide, sodium methoxide, sodium ethoxide, potassium formate, and sodium acetate.

[0017] Preferably, in step S1, the mass ratio of allyl polyoxyethylene ether, acrylic acid phosphate ester, catalyst and solvent is 1:(0.07 - 0.1):(0.05 - 0.1):(3 - 4).

[0018] Preferably, in step S1, the reaction temperature is 25 - 60°C and the time is 6 - 10 h.

[0019] Preferably, in step S2, the initiator is any one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0020] Preferably, in step S2, the chain transfer agent is any one or more of 3-mercaptopropionic acid and mercaptoethanol; the lignosulfonate is any one or more of sodium lignosulfonate, magnesium lignosulfonate, ammonium lignosulfonate, calcium lignosulfonate, and calcium ammonium lignosulfonate.

[0021] Preferably, in step S2, the mass ratio of the initiator, chain transfer agent to deionized water is (0.02 - 0.03):(0.015 - 0.02):1.

[0022] Preferably, in step S2, the mass ratio of the intermediate, deionized water, fumaric acid, lignosulfonate, initiator solution, and chain transfer agent solution is 1:(3 - 4):(0.1 - 0.5):(0.03 - 0.05):(0.01 - 0.03):(0.01 - 0.02).

[0023] Preferably, in step S2, the temperature of the first heating and stirring is 30 - 40°C, the speed is 200 - 300 rpm / min, and the time is 20 - 30 min.

[0024] Preferably, in step S2, the temperature of the second heating and stirring is 40 - 50°C, the speed is 300 - 400 rpm / min, and the time is 30 - 60 min.

[0025] Preferably, in step S2, the temperature of the third heating and stirring is 70 - 90°C, the speed is 200 - 300 rpm / min, and the time is 12 - 24 h.

[0026] Preferably, in step S2, the set time is 1 - 3 h.

[0027] Preferably, in step S3, the retarder is any one or more of sodium gluconate, sodium tripolyphosphate, citric acid, and borax.

[0028] Preferably, in step S3, the alkali solution is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0029] Preferably, in step S3, the distillation temperature is 95 - 105°C, and the time is 1 - 3 h.

[0030] Preferably, in step S3, the stabilizer is any one or more of ethylene glycol and propylene glycol

[0031] Preferably, in step S3, the mass ratio of the primary product to the retarder is 1:(0.05 - 0.1); the mass ratio of the advanced product to the stabilizer is 1:(0.01 - 0.05).

[0032] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0033] (1) The preparation system of the present invention can achieve continuous and stable production, with coordinated operation of each production link. The feeding equipment box and raw material storage tank can accurately sample and measure, ensuring high consistency and stability in the composition and performance of each batch of products. The system is equipped with perfect solid and liquid waste storage devices, reducing environmental pollution. The system design follows strict safety standards, and each device is equipped with a pressure gauge and a valve, which can effectively ensure the safety of operators and the normal operation of production equipment, reduce safety risks during the production process, improve the utilization rate of equipment, and increase production.

[0034] (2) The present invention uses allyl polyoxyethylene ether as a monomer and introduces a phosphonyl group. Allyl polyoxyethylene ether contains an allyl double bond, which has high activity and is easy to react with other monomers. The phosphonyl group has strong polarity and unique chemical activity, and can chemically react with metal ions on the surface of cement particles to form stable chemical bonds, so that the water reducer molecules are firmly adsorbed on the surface of cement particles. Compared with the adsorption method of traditional water reducer molecules, the adsorption formed by the phosphonyl group and the surface of cement particles through chemical bonds is more stable and lasting, which can effectively prevent the water reducer molecules from falling off the surface of cement particles during the processes of concrete mixing, transportation and construction, so as to ensure that the water reducer molecules can continuously play the role of dispersing cement particles and improve the performance stability of concrete.

[0035] (3) The present invention uses a phosphonyl group to modify allyl polyoxyethylene ether and polymerize it with fumaric acid to obtain a polymer with a comb-like structure. The double bond in the fumaric acid molecule can polymerize with the double bond of the phosphonyl group-modified allyl polyoxyethylene ether. After the polymerization reaction, the molecular structure of the water reducer is optimized, and the polymer molecules are more firmly and evenly adsorbed on the surface of cement particles, further enhancing the dispersing performance of the water reducer. At the same time, the optimized polymer molecular structure can better adjust the charge distribution on the surface of cement particles, increasing the electrostatic repulsion between cement particles, so as to more effectively prevent the mutual approach and aggregation of cement particles, and further improving the dispersing effect of the water reducer. The synergistic effect of introducing the phosphonyl group and the fumaric acid chain segment enables the water reducer to significantly reduce the water-cement ratio of concrete without increasing the amount of cement used, thereby increasing the water reduction rate of concrete while maintaining excellent slump retention performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the preparation system of a polycarboxylate water reducer.

[0037] Figure 2 It is a schematic diagram of the process flow of a preparation method of a polycarboxylate water reducer.

[0038] Meanings of the attached drawing reference numerals: 1. First reaction tower; 2. First filtration tower; 3. Recrystallization tower; 4. First distillation tower; 5. Drying tower; 6. Intermediate storage tank; 7. First mixing tower; 8. Second reaction tower; 9. Cooling tower; 10. Primary product storage tank; 11. Second mixing tower; 12. pH adjustment tower; 13. Second filtration tower; 14. Second distillation tower; 15. High-grade product storage tank; 16. Third mixing tower; 17. Polycarboxylate water reducer storage tank; 18. First raw material storage tank; 19. Second raw material storage tank; 20. Organic solvent storage tank; 21. First feeding equipment box; 22. First waste liquid tank; 23. Ethyl acetate storage tank; 24. First solid waste storage; 25. Second waste liquid tank; 26. Water tank; 27. Third raw material storage tank; 28. Fourth raw material storage tank; 29. Second feeding equipment box; 30. Third feeding equipment box; 31. Fourth feeding equipment box; 32. Second solid waste storage; 33. Waste water tank; 34. Fifth feeding equipment box. Detailed implementation manners

[0039] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

[0040] As Figure 1 shown, a preparation system for polycarboxylate water reducer includes a first reaction tower 1, and the first reaction tower 1 is sequentially connected to a first filtration tower 2, a recrystallization tower 3, a first distillation tower 4, a drying tower 5, an intermediate storage tank 6, a first mixing tower 7, a second reaction tower 8, a cooling tower 9, a primary product storage tank 10, a second mixing tower 11, a pH adjustment tower 12, a second filtration tower 13, a second distillation tower 14, a high-grade product storage tank 15, a third mixing tower 16, and a polycarboxylate water reducer storage tank 17 through pipelines; the first reaction tower 1 is also respectively connected to a first raw material storage tank 18, a second raw material storage tank 19, an organic solvent storage tank 20, and a first feeding equipment box 21; the recrystallization tower 3 is also connected to an ethyl acetate storage tank 23; the first mixing tower 7 is also respectively connected to a water tank 26, a third raw material storage tank 27, and a fourth raw material storage tank 28; the second reaction tower 8 is also respectively connected to a second feeding equipment box 29 and a third feeding equipment box 30; the second mixing tower 11 is also connected to a fourth feeding equipment box 31; the third mixing tower 16 is also connected to a fifth feeding equipment box 34.

[0041] The system also includes a first waste liquid tank 22, a first solid waste storage 24, a second waste liquid tank 25, a second solid waste storage 32, and a waste water tank 33; wherein, the first waste liquid tank 22 is connected to the first filtration tower 2; the first solid waste storage 24 is connected to the recrystallization tower 3; the second waste liquid tank 25 is respectively connected to the first distillation tower 4 and the drying tower 5; the second solid waste storage 32 is connected to the second filtration tower 13; the waste water tank 33 is connected to the second distillation tower 14.

[0042] In the first raw material storage tank 18 is allyl polyoxyethylene ether; in the second raw material storage tank 19 is acrylic acid phosphate; in the first feeding equipment box 21 is a catalyst; in the water tank 26 is deionized water; in the third raw material storage tank 27 is fumaric acid; in the fourth raw material storage tank 28 is lignosulfonate; in the second feeding equipment box 29 is an initiator solution; in the third feeding equipment box 30 is a chain transfer agent solution; in the fourth feeding equipment box 31 is a retarder; in the fifth feeding equipment box 34 is a stabilizer; in the first waste liquid tank 22 is stored waste organic solvent; in the second waste liquid tank 25 is stored waste ethyl acetate.

[0043] In the first reaction tower 1, recrystallization tower 3, first mixing tower 7, second reaction tower 8, cooling tower 9, second mixing tower 11 and third mixing tower 16 are provided with mechanical stirring devices, pressure gauges and thermometers; in the first distillation tower 4, drying tower 5 and second distillation tower 14 are provided with thermometers and pressure gauges; in the pH adjustment tower 12 is provided with a pH meter, and the set pH value is 6 - 7; the set temperature of the cooling tower 9 is 30 - 40 °C; valves and flow meters are provided at the inlet and outlet of the pipeline.

[0044] The main compounds used in the following examples and comparative examples are commercially available products and have not been subjected to any further purification treatment.

[0045] Example 1

[0046] As Figure 2 shown, a preparation method of a polycarboxylate water reducing agent comprises the following steps:

[0047] (1) Put 10 kg of allyl polyoxyethylene ether and 0.7 kg of acrylic acid phosphate into the first reaction tower 1, inject 30 kg of tetrahydrofuran into the first reaction tower 1 through the organic solvent storage tank 20, mix evenly, put 0.5 kg of potassium tert-butoxide catalyst into the first reaction tower 1 through the first feeding equipment box 21, and react at 60 °C for 8 h to obtain a crude intermediate product; the crude intermediate product enters the first filtration tower 2 for solid-liquid separation, the waste liquid is concentrated into the first waste liquid tank 22 through the pipeline, the collected solid is put into the recrystallization tower 3, the ethyl acetate storage tank 23 injects ethyl acetate into the tower, and stir at 60 °C to accelerate the dissolution of the solid; the insoluble impurities enter the first solid waste storage 24, and the liquid enters the first distillation tower 4 to remove the excess ethyl acetate, and the waste ethyl acetate enters the second waste liquid tank 25 through the pipeline, and the intermediate enters the drying tower 5 and is dried at 60 °C for 12 h, and the ethyl acetate vapor enters the second waste liquid tank 25 through the pipeline, and the dried solid is the intermediate and is stored in the intermediate storage tank 6.

[0048] (2) Dissolve 0.02 kg of sodium persulfate in 1 kg of deionized water to obtain an initiator solution, and store it in the second feeding equipment tank 29. Dissolve 0.015 kg of mercaptoethanol in 1 kg of deionized water to obtain a chain transfer agent solution, and store it in the third feeding equipment tank 30. Put 10 kg of the intermediate into the first mixing tower 7, and the water tank 26 injects 30 kg of deionized water into the tower. Stir at 40 °C and 200 rpm / min for 30 min to fully dissolve the intermediate. Then add 1 kg of fumaric acid and 0.3 kg of sodium lignosulfonate into the first mixing tower 7, and stir at 50 °C and 300 rpm / min for 60 min to fully mix the three substances to obtain a reaction solution.

[0049] (3) All the reaction solution in step (2) enters the second reaction tower 8. Add 0.1 kg of the initiator solution and 0.1 kg of the chain transfer agent solution into the second reaction tower 8 within 2 h, and react at 80 °C and 300 rpm / min for 18 h to obtain a primary product. The primary product is injected into the cooling tower 9 for cooling, and then enters the primary product storage tank 10 for storage.

[0050] (4) Put 10 kg of the primary product into the second mixing tower 11, add 0.5 kg of sodium tripolyphosphate, mix evenly, and then inject it into the pH adjustment tower 12. Adjust the pH value to 6.5 with sodium hydroxide solution. The obtained intermediate product is injected into the second filtration tower 13. The separated insoluble solid impurities and flocculent precipitates enter the second solid waste storage 32, and the liquid is injected into the distillation tower 14. Distill at 100 °C for 2 h, and discharge the excess water into the waste water tank 33 to obtain a high-grade product, which is stored in the high-grade product storage tank 15.

[0051] (5) Put 10 kg of the high-grade product into the third mixing tower 16, add 0.1 kg of ethylene glycol to obtain a polycarboxylate superplasticizer, and store it in the polycarboxylate superplasticizer storage tank 17.

[0052] Example 2

[0053] As Figure 2 shown, a preparation method of a polycarboxylate superplasticizer includes the following steps:

[0054] (1) Put 10 kg of allyl polyoxyethylene ether and 0.85 kg of acrylic acid phosphate into the first reaction tower 1. Inject 30 kg of tetrahydrofuran into the first reaction tower 1 through the organic solvent storage tank 20, mix evenly, and put 0.75 kg of potassium tert-butoxide catalyst into the first reaction tower 1 through the first feeding equipment box 21. React at 60 °C for 8 h to obtain a crude intermediate product. The crude intermediate product enters the first filtration tower 2 for solid-liquid separation. The waste liquid is concentrated into the first waste liquid tank 22 through a pipeline. Collect the solid and put it into the recrystallization tower 3. Inject ethyl acetate into the tower from the ethyl acetate storage tank 23 and stir at 60 °C to accelerate the dissolution of the solid. The insoluble impurities enter the first solid waste storage 24, and the liquid enters the first distillation tower 4 to remove the excess ethyl acetate. The waste ethyl acetate enters the second waste liquid tank 25 through a pipeline. The intermediate enters the drying tower 5 and is dried at 60 °C for 12 h. The ethyl acetate vapor enters the second waste liquid tank 25 through a pipeline. The dried solid is the intermediate and is stored in the intermediate storage tank 6.

[0055] (2) Dissolve 0.025 kg of sodium persulfate in 1 kg of deionized water to obtain an initiator solution, and store it in the second feeding equipment box 29. Dissolve 0.0175 kg of mercaptoethanol in 1 kg of deionized water to obtain a chain transfer agent solution, and store it in the third feeding equipment box 30. Put 10 kg of the intermediate into the first mixing tower 7. Inject 30 kg of deionized water into the tower from the water tank 26 and stir at 40 °C and 200 rpm for 30 min to fully dissolve the intermediate. Then add 3 kg of fumaric acid and 0.4 kg of sodium lignosulfonate into the first mixing tower 7 and stir at 50 °C and 300 rpm for 60 min to fully mix the three substances to obtain a reaction solution.

[0056] (3) All the reaction solution in step (2) enters the second reaction tower 8. Add 0.2 kg of the initiator solution and 0.15 kg of the chain transfer agent solution into the second reaction tower 8 within 2 h. React at 80 °C and 300 rpm for 18 h to obtain a primary product. The primary product is injected into the cooling tower 9 for cooling and then stored in the primary product storage tank 10.

[0057] (4) Put 10 kg of the primary product into the second mixing tower 11, add 0.75 kg of sodium tripolyphosphate, mix evenly, and then inject it into the pH adjustment tower 12. Adjust the pH value to 6.5 with sodium hydroxide solution. The obtained intermediate product is injected into the second filtration tower 13. The separated insoluble solid impurities and flocculent precipitates enter the second solid waste storage 32, and the liquid is injected into the distillation tower 14. Distill at 100 °C for 2 h, and discharge the excess water into the waste water tank 33 to obtain a high-grade product, which is stored in the high-grade product storage tank 15.

[0058] (5) Put 10 kg of the high-grade product into the third mixing tower 16, add 0.3 kg of ethylene glycol to obtain a polycarboxylate water reducer, and store it in the polycarboxylate water reducer storage tank 17.

[0059] Example 3

[0060] As Figure 2 shown, a preparation method of a polycarboxylate water reducer includes the following steps:

[0061] (1) Put 10 kg of allyl polyoxyethylene ether and 1 kg of acrylic acid phosphate into the first reaction tower 1. Inject 30 kg of tetrahydrofuran into the first reaction tower 1 through the organic solvent storage tank 20, mix evenly, and put 1 kg of potassium tert-butoxide catalyst into the first reaction tower 1 through the first feeding equipment box 21. React at 60 °C for 8 h to obtain a crude intermediate product. The crude intermediate product enters the first filtration tower 2 for solid-liquid separation. The waste liquid is concentrated into the first waste liquid tank 22 through a pipeline. Collect the solid and put it into the recrystallization tower 3. Inject ethyl acetate into the tower from the ethyl acetate storage tank 23 and stir at 60 °C to accelerate the dissolution of the solid. Insoluble impurities enter the first solid waste storage 24, and the liquid enters the first distillation tower 4 to remove the excess ethyl acetate. The waste ethyl acetate enters the second waste liquid tank 25 through a pipeline. The intermediate enters the drying tower 5 and is dried at 60 °C for 12 h. The ethyl acetate vapor enters the second waste liquid tank 25 through a pipeline. The dried solid is the intermediate and is stored in the intermediate storage tank 6.

[0062] (2) Dissolve 0.03 kg of sodium persulfate in 1 kg of deionized water to obtain an initiator solution, and store it in the second feeding equipment box 29. Dissolve 0.02 kg of mercaptoethanol in 1 kg of deionized water to obtain a chain transfer agent solution, and store it in the third feeding equipment box 30. Put 10 kg of the intermediate into the first mixing tower 7. Inject 30 kg of deionized water into the tower from the water tank 26 and stir at 40 °C and 200 rpm for 30 min to fully dissolve the intermediate. Then add 5 kg of fumaric acid and 0.5 kg of sodium lignosulfonate into the first mixing tower 7 and stir at 50 °C and 300 rpm for 60 min to fully mix the three substances to obtain a reaction solution.

[0063] (3) All the reaction solution in step (2) enters the second reaction tower 8. Add 0.3 kg of the initiator solution and 0.2 kg of the chain transfer agent solution into the second reaction tower 8 within 2 h. React at 80 °C and 300 rpm for 18 h to obtain a primary product. The primary product is injected into the cooling tower 9 for cooling and then stored in the primary product storage tank 10.

[0064] (4) Put 10 kg of the primary product into the second mixing tower 11, add 1 kg of sodium tripolyphosphate, mix evenly, then inject it into the pH adjustment tower 12, adjust the pH value to 6.5 with sodium hydroxide solution. The obtained intermediate product is injected into the second filtration tower 13. The insoluble solid impurities and flocculent precipitates separated enter the second solid waste storage 32, and the liquid is injected into the distillation tower 14. Distill at 100 °C for 2 h, discharge the excess water into the waste water tank 33 to obtain the high-grade product, which is stored in the high-grade product storage tank 15.

[0065] (5) Put 10 kg of the high-grade product into the third mixing tower 16, add 0.5 kg of ethylene glycol to obtain the polycarboxylate water reducer, which is stored in the polycarboxylate water reducer storage tank 17.

[0066] Comparative Example 1

[0067] As Figure 2 shown, a preparation method of a polycarboxylate water reducer, which is different from Example 3 in that acrylic acid phosphate is not added in step (1).

[0068] Comparative Example 2

[0069] As Figure 2 shown, a preparation method of a polycarboxylate water reducer, which is different from Example 3 in that fumaric acid is not added in step (2).

[0070] Performance test: Prepare reference concrete according to the method of JGJ 55 "Technical Specification for Mix Proportion Design of Ordinary Concrete", and add the polycarboxylate water reducers prepared in Examples 1 - 3 and Comparative Examples 1 - 2 to the reference concrete formula to prepare the tested concrete. Test the water reduction rate, bleeding rate, air content, slump, shrinkage ratio and compressive strength ratio of the samples according to the method in GB 8076-2008.

[0071] Table 1 Test data of water reduction rate, bleeding rate and air content of the tested concrete

[0072]

[0073]

[0074] According to the data in Table 1, the water reduction rate of the concrete added with the water reducers prepared in Examples 1 to 3 is above 30%, and the bleeding rate is below 30%. The water reducers show good water reduction effects. The cement particles in the obtained concrete are evenly dispersed and have good fluidity. While for the concrete added with the water reducers prepared in Comparative Examples 1 to 2, the water reduction rate is below 20%, and the bleeding rate exceeds 35%. During the processes of mixing, transporting, vibrating and pumping, the phenomenon of water floating up occurs. The air content of the concrete added with the water reducers prepared in Examples 1 to 3 is between 3% and 5%. Within a certain range, the air content is positively correlated with the water reduction performance of the water reducer. Appropriately increasing the air content can effectively improve the workability and fluidity of the concrete, and improve the slump (the air content is 3.0 - 8.0%) and the anti-permeability performance (the air content is 3.0 - 5.0%).

[0075] Table 2 Test data of the shrinkage ratio and slump of the tested concrete

[0076] Shrinkage ratio (%) Slump (cm) Example 1 95.3 17.8 Example 2 95.8 18.4 Example 3 96.6 18.8 Comparative Example 1 113.5 12.5 Comparative Example 2 116.5 13.8

[0077] According to the data in Table 2, the shrinkage ratio of the concrete added with the water reducers prepared in Examples 1 to 3 is significantly lower than that of the concrete added with the water reducers prepared in Comparative Examples 1 to 2. A relatively large shrinkage ratio of the concrete will cause the concrete to shrink, generate cracks, and affect the stability and safety of the concrete structure. The water reducers prepared in Examples 1 to 3 can improve the fluidity of the concrete, optimize the pore structure of the concrete, and reduce the total shrinkage ratio. The slump of the concrete added with the water reducers prepared in Examples 1 to 3 is higher than that of the concrete added with the water reducers prepared in Comparative Examples 1 to 2. The experimental results verify that increasing the air content of the concrete by the water reducer can effectively improve the slump of the concrete. The larger the slump, the better the fluidity of the concrete, which is easy for construction operation and uniform compaction.

[0078] Table 3 Test data of the compressive strength ratio of the tested concrete

[0079]

[0080]

[0081] According to the data in Table 3, the compressive strength ratio of the concrete added with the water reducers prepared in Examples 1 to 3 at 7 days is higher than 160%. The compressive strength ratio of the concrete added with the water reducers prepared in Comparative Examples 1 to 2 is significantly lower than that of the concrete added with the water reducers prepared in Examples 1 to 3; on the 14th day and the 28th day, the compressive strength ratios of the concrete added with the water reducers in Examples 1 to 3 and Comparative Examples 1 to 2 both decrease, and the decreasing amplitude of the compressive strength ratio of the concrete added with the water reducers in Comparative Examples 1 to 2 is higher than that of the concrete added with the water reducers in Examples 1 to 3.

[0082] In concrete preparation, the smaller the water-cement ratio, the higher the strength of the concrete. Adding the water-reducing agents prepared in Examples 1 to 3 effectively reduces the amount of water used in preparing concrete, makes the cement particles disperse evenly, reduces the number of pores inside the concrete, improves the density, makes the structure more compact, and thus enhances the compressive strength of the concrete.

[0083] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A system for preparing a polycarboxylate water-reducing agent, comprising a first reaction tower (1), characterized in that: The first reaction tower (1) is connected to the first filtration tower (2), the recrystallization tower (3), the first distillation tower (4), the drying tower (5), the intermediate storage tank (6), the first mixing tower (7), the second reaction tower (8), the cooling tower (9), the primary product storage tank (10), the second mixing tower (11), the pH adjustment tower (12), the second filtration tower (13), the second distillation tower (14), the advanced product storage tank (15), the third mixing tower (16), and the polycarboxylate water reducer storage tank (17) in sequence through pipelines; the first reaction tower (1) is also connected to the first raw material storage tank (18), the second raw material storage tank (19), the organic solvent storage tank (20) and the first feeding equipment box (21) are connected; the recrystallization tower (3) is also connected to the ethyl acetate storage tank (23); the first mixing tower (7) is also respectively connected to the water tank (26), the third raw material storage tank (27) and the fourth raw material storage tank (28); the second reaction tower (8) is also respectively connected to the second feeding equipment box (29) and the third feeding equipment box (30); the second mixing tower (11) is also connected to the fourth feeding equipment box (31); and the third mixing tower (16) is also connected to the fifth feeding equipment box (34).

2. A system for preparing a polycarboxylate water-reducing agent according to claim 1, characterized in that: The system further comprises a first waste liquid tank (22), a first solid waste storage (24), a second waste liquid tank (25), a second solid waste storage (32) and a waste water tank (33); wherein the first waste liquid tank (22) is connected to the first filtering tower (2); the first solid waste storage (24) is connected to the recrystallization tower (3); the second waste liquid tank (25) is respectively connected to the first distillation tower (4) and the drying tower (5); the second solid waste storage (32) is connected to the second filtering tower (13); and the waste water tank (33) is connected to the second distillation tower (14).

3. A system for preparing a polycarboxylate water-reducing agent according to claim 1, characterized in that: The first raw material storage tank (18) contains allyl polyoxyethylene ether; the second raw material storage tank (19) contains acrylic acid phosphate; the first feeding equipment box (21) contains a catalyst; the water tank (26) contains deionized water; the third raw material storage tank (27) contains fumaric acid; the fourth raw material storage tank (28) contains lignin sulfonate; the second feeding equipment box (29) contains an initiator solution; the third feeding equipment box (30) contains a chain transfer agent solution; the fourth feeding equipment box (31) contains a retarder; and the fifth feeding equipment box (34) contains a stabilizer.

4. A system for preparing a polycarboxylate water-reducing agent according to claim 2, characterized in that: The first waste liquid tank (22) stores waste organic solvents; the second waste liquid tank (25) stores waste ethyl acetate.

5. A system for preparing a polycarboxylate water-reducing agent according to claim 2, characterized in that: The first reaction tower (1), the recrystallization tower (3), the first mixing tower (7), the second reaction tower (8), the cooling tower (9), the second mixing tower (11) and the third mixing tower (16) are all provided with a mechanical stirring device, a pressure gauge and a thermometer; the first distillation tower (4), the drying tower (5) and the second distillation tower (14) are all provided with a thermometer and a pressure gauge; the pH adjustment tower (12) is provided with a pH meter, and the pH value is set to 6 to 7; the cooling tower (9) is set to a temperature of 30 to 40°C; and valves and flow meters are provided at the inlet and outlet of the pipeline.

6. A method for preparing a polycarboxylate water-reducing agent, characterized in that: A preparation system for a polycarboxylate water reducer according to any one of claims 1 to 5 is implemented, based on allyl polyoxyethylene ether, after phosphonyl functionalization, polymerized with fumaric acid to obtain the polycarboxylate water reducer, and the preparation steps include: Step S1, allyl polyoxyethylene ether, acrylic acid phosphate and a catalyst are mixed with an organic solvent in a first reaction tower (1), and reacted to obtain a crude intermediate product, and the crude intermediate product enters a recrystallization tower (3), and is recrystallized with ethyl acetate to obtain an intermediate; Step S2, the initiator and the chain transfer agent are respectively dissolved in deionized water to obtain an initiator solution and a chain transfer agent solution. In a first mixing tower (7), the intermediate is mixed with deionized water, heated and stirred for the first time to dissolve, fumaric acid and lignin sulfonate are added, heated and stirred for the second time to mix evenly to obtain a reaction liquid, the reaction liquid enters a second reaction tower (8), heated and stirred for the third time to start the reaction, and the initiator solution and the chain transfer agent solution are added to the reaction liquid in batches within a set time after the start of the reaction to obtain a primary product; Step S3: The primary product is mixed with a retarder in a second mixing tower (11) to obtain an intermediate product. The intermediate product is adjusted to a pH of 6 to 7 with an alkaline solution in a pH adjusting tower (12). Then, impurities are filtered in a second filtering tower (13). The filtrate enters a second distillation tower (14) for distillation to obtain a higher-level product. The higher-level product and a stabilizer are stirred and mixed uniformly in a third mixing tower (16) to obtain a polycarboxylate water-reducing agent.

7. The method for preparing a polycarboxylate water-reducing agent according to claim 6, characterized in that: In step S1, the organic solvent is any one or more of N,N'-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide; the catalyst is any one or more of potassium tert-butoxide, sodium methoxide, sodium ethoxide, potassium formate, and sodium acetate; the mass ratio of allyl polyoxyethylene ether, acrylic acid phosphate, catalyst, and solvent is 1: (0.07-0.1): (0.05-0.1): (3-4); the reaction temperature is 25-60°C, and the reaction time is 6-10 hours.

8. The method for preparing a polycarboxylate water-reducing agent according to claim 6, characterized in that: In the step S2, the initiator is any one or more of sodium persulfate, potassium persulfate, and ammonium persulfate; the chain transfer agent is any one or more of 3-mercaptopropionic acid and mercaptoethanol; the lignin sulfonate is any one or more of sodium lignin sulfonate, magnesium lignin sulfonate, ammonium lignin sulfonate, calcium lignin sulfonate, and calcium ammonium lignin sulfonate; the mass ratio of the initiator, the chain transfer agent, and the deionized water is (0.02-0.03): (0.015-0.02): 1; the mass ratio of the intermediate, deionized water, fumaric acid, lignin sulfonate, initiator solution, and chain transfer agent solution is 1: (3-4): (0.1-0.5): (0.03-0.05): (0.01-0.03): (0.01-0.02).

9. The method for preparing a polycarboxylate water-reducing agent according to claim 6, characterized in that: In step S2, the first heating and stirring temperature is 30-40°C, the speed is 200-300rpm / min, and the time is 20-30min; the second heating and stirring temperature is 40-50°C, the speed is 300-400rpm / min, and the time is 30-60min; the third heating and stirring temperature is 70-90°C, the speed is 200-300rpm / min, and the time is 12-24h; the set time is 1-3h.

10. The method for preparing a polycarboxylate water-reducing agent according to claim 6, characterized in that: In step S3, the retarder is any one or more of sodium gluconate, sodium tripolyphosphate, citric acid, and borax; the alkaline solution is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; the distillation temperature is 95-105° C., and the time is 1-3 hours; the stabilizer is any one or more of ethylene glycol and propylene glycol; the mass ratio of the primary product to the retarder is 1:(0.05-0.1); the mass ratio of the advanced product to the stabilizer is 1:(0.01-0.05).

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