Mud-resistant polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention relates to a mud-resistant polycarboxylic acid water reducing agent and a preparation method thereof, and the mud-resistant polycarboxylic acid water reducing agent is prepared from the following raw materials in parts by weight: 90-260 parts of allyl-terminated polyether monomer; 20 to 32 parts of unsaturated acid monomer; 8-15 parts of an unsaturated ester monomer; 4-8 parts of a quaternary ammonium salt compound; 1.5 to 3.0 parts of an oxidizing agent; 0.2 to 0.4 part of a reducing agent; 0.8 to 1.5 parts of a chain transfer agent; and water; wherein the allyl-terminated polyether monomer is prepared from the following raw materials: unsaturated alcohol, an allyl compound and a basic catalyst. The polycarboxylate superplasticizer prepared by the method disclosed by the invention has the advantages of low mixing amount, high water reduction, good workability, low mixing amount sensitivity, excellent mud resistance, capability of remarkably improving the dispersion and adsorption performance of concrete, wide application range of mud content in sand and gravel materials and the like.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, in particular to a mud-blocking polycarboxylate water-reducing agent and a preparation method thereof. Background Art

[0002] Concrete admixtures are the most widely studied and applied concrete additives. They can effectively reduce cement usage, water usage and improve concrete strength while maintaining the workability of concrete. Among them, polycarboxylate water reducers are widely used in various construction projects due to their advantages such as low dosage, good slump retention, strong controllable molecular structure and green production process.

[0003] However, with the rapid development of the construction industry, the consumption of cement and sand and gravel in engineering construction has continued to rise, resulting in an increasingly tight supply of sand and gravel resources. The problem of shortage of natural sand and stone resources has gradually emerged across the country. This resource shortage directly leads to large fluctuations in the quality of sand and gravel materials, especially the frequent high and unstable mud content in sand and gravel. Due to the differences in raw materials and the influence of environmental conditions, the problem of insufficient fluidity or rapid loss of fluidity of freshly mixed concrete often occurs, and it may also cause concrete segregation, slurry exudation and other phenomena, thereby increasing the difficulty of controlling concrete production. The root cause of these problems lies in the lack of adaptability between admixtures and concrete raw materials.

[0004] In concrete with high clay or mud content, the dispersion performance of admixtures will be significantly reduced, resulting in reduced fluidity and strength of concrete. In addition, the performance stability of existing water reducers under different temperature and humidity conditions is poor, and there are also limitations in their adaptability to different brands and types of cement, fine aggregate and coarse aggregate.

[0005] In order to solve the above problems, the methods usually adopted include compounding mud inhibitors, water retaining agents or other additives to improve performance. Although these methods have alleviated the problem of large slump loss of concrete to a certain extent, they also bring challenges such as increased costs and prolonged subsequent setting time and reduced strength. Another method is to use mud-resistant water reducers. This type of water reducer has good dispersion performance in concrete with high clay or mud content by optimizing molecular structure and formula design. It also has excellent environmental adaptability and wide adaptability to a variety of raw materials.

[0006] Therefore, it is of great practical significance and technical value to develop a low-sensitivity mud-resistant polycarboxylate water-reducing agent and a preparation method thereof to meet the demand for high-performance admixtures in modern concrete engineering. Summary of the invention

[0007] Based on this, it is necessary to provide a mud-resistant polycarboxylic acid water-reducing agent to effectively solve the problem that the dispersibility of the admixture will be significantly reduced in concrete with a high content of clay or mud.

[0008] To achieve the above object, the present invention provides a technical solution:

[0009] A sludge-blocking polycarboxylate water-reducing agent, wherein the raw materials for preparing the sludge-blocking polycarboxylate water-reducing agent include, by weight:

[0010]

[0011] The raw materials for preparing the allyl-terminated polyether monomer include unsaturated alcohol, allyl compound and alkaline catalyst.

[0012] Specifically, the reducing agent includes at least one of ascorbic acid, sodium formaldehyde sulfoxylate, sodium sulfite, bleaching powder, sodium bisulfite and sodium hypophosphite, wherein the sodium hypophosphite can also serve as a chain transfer agent;

[0013] The oxidant comprises at least one of hydrogen peroxide, sodium peroxide, potassium peroxide, magnesium peroxide, sodium persulfate, ammonium persulfate, sodium dichromate, potassium dichromate and potassium permanganate;

[0014] The chain transfer agent includes at least one of thioglycolic acid, sodium hypophosphite, trisodium phosphate, mercaptopropionic acid, mercaptoethanol and thioglycolic acid;

[0015] The unsaturated acid monomer includes at least one of acrylic acid, methacrylic acid, fumaric acid, maleic anhydride and itaconic acid;

[0016] The unsaturated ester monomer includes at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and vinyl acetate.

[0017] Furthermore, the allyl-terminated polyether monomer has the following structural formula:

[0018]

[0019] Wherein, R1 is CH3-, CH3CH2- or (CH3)2CH-;

[0020] R2 is CH3-, CH3CH2- or (CH3)2CH-;

[0021] R3 is CH3-, CH3CH2- or (CH3)2CH-.

[0022] Furthermore, the allyl compound includes at least one of allyl chloride and allyl bromide.

[0023] Furthermore, the alkaline catalyst includes at least one of potassium hydroxide, sodium hydroxide and triethanolamine.

[0024] Furthermore, the raw materials for preparing the allyl-terminated polyether monomer also include phosphoric acid, and the weight ratio of the unsaturated alcohol, the allyl chloride compound, the alkaline catalyst and the phosphoric acid is (18-20): (4-8): (8-12): (0.3-0.6);

[0025] Further, the structural formula of the quaternary ammonium salt compound is as follows:

[0026]

[0027]

[0028] One of them.

[0029] Furthermore, in terms of parts by weight, the raw materials for preparing the mud-blocking polycarboxylate water-reducing agent include:

[0030] 0.01-0.02 parts of ferrous sulfate.

[0031] The present invention also provides a method for preparing a mud-blocking polycarboxylate water-reducing agent, comprising the steps of:

[0032] S100, stirring the allyl-terminated polyether monomer, the oxidant and water evenly to completely dissolve them, to obtain a base solution;

[0033] S200, adding liquid A and liquid B dropwise to the base liquid, and after the addition is completed, continuing the heat preservation reaction for 1h to 2h to obtain the mud-blocking polycarboxylate water-reducing agent;

[0034] Wherein, the liquid A is an aqueous solution of an unsaturated acid monomer, an unsaturated ester monomer and a quaternary ammonium salt compound;

[0035] Liquid B is an aqueous solution of a reducing agent and a chain transfer agent.

[0036] In some embodiments, ferrous sulfate is added when preparing the mud-blocking polycarboxylate water-reducing agent, and the specific steps are as follows:

[0037] S100, stirring the allyl-terminated polyether monomer, the oxidant, ferrous sulfate and water evenly to completely dissolve them, to obtain a base solution;

[0038] S200, adding liquid A and liquid B dropwise to the base liquid, and after the addition is completed, continuing the heat preservation reaction for 1h to 2h to obtain the mud-blocking polycarboxylate water-reducing agent;

[0039] Wherein, the liquid A is an aqueous solution of an unsaturated acid monomer, an unsaturated ester monomer and a quaternary ammonium salt compound;

[0040] Furthermore, the preparation method of the allyl-terminated polyether monomer comprises the steps of:

[0041] adding a basic catalyst to an unsaturated alcohol to obtain a first mixture;

[0042] In a water bath maintained at 55° C. to 65° C., the allyl compound is added dropwise to the first mixture, and the mixture is stirred at a constant temperature for 4 to 6 hours. After the addition is completed, the reaction is continued at a constant temperature for 1 to 2 hours to obtain the allyl-terminated polyether monomer.

[0043] Furthermore, the preparation method of the quaternary ammonium salt compound monomer comprises the steps of:

[0044] dissolving dopamine in an acidic solution to obtain a dopamine solution;

[0045] dissolving an aldehyde compound in an alcohol solution to obtain an aldehyde compound solution;

[0046] Adding an aldehyde compound solution to the dopamine solution, stirring for 18 to 24 hours, and adjusting the pH value to neutral to obtain compound A;

[0047] In a water bath at 55°C to 65°C, the compound A is dissolved in an alcohol solution, a base is added, and after reacting for 3h to 5h, a 3-chloro-2-hydroxypropyltrimethylammonium chloride solution is added dropwise, and the reaction is continued for 4h to 5h to obtain a quaternary ammonium salt compound. More specifically, the quaternary ammonium salt compound can be cleaned with a cleaning solvent, the cleaning solvent includes at least one of acetone, ethanol and water; the alcohol solution includes at least one of methanol, ethanol, isopropanol, n-butanol and ethylene glycol.

[0048] The weight ratio of dopamine, aldehyde compound and acidic solution is 1: (0.75-1.25): (50-62.5); specifically, the aldehyde compound includes at least one of salicylaldehyde, o-vanillin, benzaldehyde, 4-bromo-2-hydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde;

[0049] The acidic solution includes at least one of acetic acid, propionic acid, formic acid, and dilute hydrochloric acid.

[0050] Beneficial effects of the present invention:

[0051] The present invention has the following advantages:

[0052] 1. The present invention introduces an allyl-terminated polyether monomer into the anti-mud type polycarboxylate water-reducing agent, thereby introducing a part of a short side chain structure into the molecular structure of the anti-mud type polycarboxylate water-reducing agent, thereby enhancing its steric hindrance effect and reducing the branch density, thereby obtaining a polymer with a more uniform side chain distribution, so that the anti-mud type polycarboxylate water-reducing agent has better water-reducing performance and excellent low sensitivity.

[0053] In addition, the allyl-terminated polyether monomer can improve the resistance of the water reducer to mud, and even in concrete containing a high content of clay or mud, it can maintain good dispersion performance and improve the fluidity and strength of the concrete.

[0054] Enhanced stability: Allyl-terminated polyether monomers can improve the stability of water reducers under different environmental conditions and reduce the impact of external factors on the performance of water reducers.

[0055] 2. The present invention introduces quaternary ammonium salt compounds into the mud-blocking polycarboxylate water-reducing agent, which can increase the steric hindrance effect of the molecules, more effectively disperse cement particles, and improve the fluidity and working performance of concrete. It enhances the adsorption capacity of the water-reducing agent on the surface of cement particles and forms a more stable adsorption layer. It is beneficial to the wetting and adsorption of cement, and improves the dispersibility and fluidity of concrete;

[0056] 3. In the preparation method of the present invention, unsaturated ester monomers, unsaturated carboxylic acid monomers, reducing agents and water are copolymerized to introduce carboxylate groups and ester groups into the molecular structure of the polymer.

[0057] The block polyether macromonomer in the side chain of the water reducer is connected to the main chain of the water reducer through oxygen, which reduces the spatial resistance to the swing of the polyether macromonomer in the side chain of the water reducer, makes the activity freedom of the polyether macromonomer in the side chain of the water reducer higher, improves the wrapping and entanglement of the polyether macromonomer in the side chain of the water reducer, and thus has a strong adsorption capacity; at the same time, the ester group is continuously hydrolyzed during the cement hydration process, continues to react with the cement hydration products, inhibits the growth of Ca(OH)2 and AFt crystal nuclei, slows down the hydration rate, and prolongs the cement hydration induction period, thereby playing a role in improving the dispersion retention.

[0058] 4. The mud-resistant polycarboxylic acid water-reducing agent prepared by the method of the present invention has the advantages of low dosage, high water reduction, good workability, low dosage sensitivity and excellent mud resistance, can significantly improve the dispersion and adsorption performance of concrete, and has a wide range of adaptability to the mud content of sand and gravel. DETAILED DESCRIPTION

[0059] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0060] In the examples, the test methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0061] 1. Preparation of Allyl-Terminated Polyether Monomer A

[0062] 1. Allyl terminated polyether monomer A1:

[0063] 200 parts of 3,7-dimethyl-6-octen-1-ol were added to a four-necked flask, and 60 parts of potassium hydroxide were added, and the temperature was maintained at 55°C in a water bath under a nitrogen atmosphere. Subsequently, 100 parts of allyl chloride compound were slowly added dropwise, and the mixture was stirred at this temperature for 4 hours. After the addition was completed, the mixture was kept warm at the same temperature for 2 hours. Finally, 5 parts of phosphoric acid were added for neutralization treatment, and then a refining treatment was performed to obtain the allyl-terminated polyether monomer A1.

[0064] 2. Allyl terminated polyether monomer A2:

[0065] 200 parts of hydroxycitronellol were added to a four-necked flask, and 60 parts of potassium hydroxide were added, and the temperature was maintained at 55°C in a water bath under a nitrogen atmosphere. Subsequently, 100 parts of allyl chloride compound were slowly added dropwise, and the mixture was stirred at this temperature for 4 hours. After the addition was completed, the mixture was kept warm at the same temperature for 2 hours. Finally, 5 parts of phosphoric acid were added for neutralization treatment, and then a refining treatment was performed to obtain the allyl-terminated polyether monomer A2.

[0066] 2. Preparation of Quaternary Ammonium Salt Compound B

[0067] 1. Preparation of quaternary ammonium salt compound B1:

[0068] 1.6 g of dopamine was dissolved in 80 mL of acetic acid, and then 1.2 g of salicylaldehyde was dissolved in 100 mL of anhydrous methanol and added to the dopamine solution, and stirred for 18 hours. The pH value was adjusted to 7 using sodium hydroxide solution, and then washed with an appropriate washing solvent and vacuum dried to obtain compound A.

[0069] 1.6 g of compound A was dissolved in 100 mL of isopropanol, 10 mL of 40% sodium hydroxide was added, and the mixture was reacted in a water bath at 55° C. for 4 h. Subsequently, 30 mL of an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride (40 wt.%) was slowly added dropwise under the same water bath conditions, the temperature was controlled at 60° C., and the reaction was continued for 4-5 hours. Finally, the obtained product was washed with an alcohol solution and dried under vacuum to obtain a quaternary ammonium salt compound B1.

[0070] 2. Preparation of quaternary ammonium salt compound B2:

[0071] 1.6 g of dopamine was dissolved in 80 mL of acetic acid, and then 2.0 g of 4-bromo-2-hydroxybenzaldehyde was dissolved in 100 mL of anhydrous methanol and added to the dopamine solution, and stirred for 24 hours. The pH value was adjusted to neutral using a sodium hydroxide solution, and then washed with an appropriate washing solvent and vacuum dried to obtain compound A.

[0072] 1.6 g of compound A was dissolved in 100 mL of isopropanol, 10 mL of 40% sodium hydroxide was added, and the mixture was reacted in a water bath at 55° C. for 4 h. Subsequently, 30 mL of an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride (40 wt.%) was slowly added dropwise under the same water bath conditions, the temperature was controlled at 60° C., and the reaction was continued for 4 hours. Finally, the resulting product was washed with an alcohol solution and dried under vacuum to obtain a quaternary ammonium salt compound B2.

[0073] 3. Preparation of quaternary ammonium salt compound B3:

[0074] 1.6 g of dopamine was dissolved in 80 mL of acetic acid, and then 1.5 g of o-vanillin was dissolved in 100 mL of anhydrous methanol and added to the dopamine solution, and stirred for 20 hours. The pH value was adjusted to neutral using a sodium hydroxide solution, and then washed with an appropriate washing solvent and vacuum dried to obtain compound A.

[0075] Next, 1.6 g of compound A was dissolved in 100 mL of isopropanol, 10 mL of 40% sodium hydroxide was added, and the mixture was reacted in a water bath at 55° C. for 4 h. Subsequently, 30 mL of an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride (40 wt.%) was slowly added dropwise under the same water bath conditions, the temperature was controlled at 60° C., and the reaction was continued for 5 hours. Finally, the product was washed with an alcohol solution and dried under vacuum to obtain a quaternary ammonium salt compound B3.

[0076] 3. Preparation of mud-blocking polycarboxylate water reducer

[0077] Example 1

[0078] 180 g of allyl-terminated polyether monomer A1 and 300 g of water were placed in a four-necked flask, stirred and dissolved, and then 0.01 g of ferrous sulfate and 1.5 g of hydrogen peroxide were added to obtain a base solution;

[0079] The reaction temperature was adjusted to 20°C, and liquid A and liquid B were simultaneously added dropwise to the bottom liquid in the four-necked flask. After the addition was completed, the mixture was kept warm for 1 hour, and then liquid alkali was added for neutralization to obtain a sludge-resistant polycarboxylic acid water-reducing agent.

[0080] Liquid A is a solution prepared from 22g acrylic acid, 8g hydroxyethyl acrylate, 4g quaternary ammonium salt compound B1 and 10g water, and the dropwise addition time of liquid A is 60min;

[0081] Solution B is a solution prepared from 0.2 g of ascorbic acid, 0.22 g of mercaptoethanol and 42 g of water, and the dropwise addition time of solution B is 60 min.

[0082] Example 2

[0083] 180 g of allyl-terminated polyether monomer A2 and 300 g of water were placed in a four-necked flask, stirred and dissolved, and then 0.01 g of ferrous sulfate and 1.5 g of hydrogen peroxide were added to obtain a base solution;

[0084] The reaction temperature was adjusted to 35°C, and liquid A and liquid B were simultaneously added dropwise to the bottom liquid in the four-necked flask. After the addition was completed, the mixture was kept warm for 1 to 2 hours, and then liquid alkali was added for neutralization to obtain a sludge-resistant polycarboxylic acid water-reducing agent.

[0085] Liquid A is a solution prepared from 22g methacrylic acid, 8g hydroxypropyl acrylate, 4g quaternary ammonium salt compound B2 and 10g water, and the dropwise addition time of liquid A is 50min;

[0086] Liquid B is a solution prepared from 0.2 g of bleaching powder, 1.5 g of sodium hypophosphite and 42 g of water. The addition time of liquid B is ~80 min.

[0087] Example 3

[0088] 180 g of allyl-terminated polyether monomer A1 and 300 g of water were placed in a four-necked flask, stirred and dissolved, and then 0.01 g of ferrous sulfate and 1.5 g of hydrogen peroxide were added to obtain a base solution;

[0089] The reaction temperature was adjusted to 30°C, and liquid A and liquid B were simultaneously added dropwise to the bottom liquid in the four-necked flask. After the addition was completed, the mixture was kept warm for 2 hours, and then liquid alkali was added for neutralization to obtain a sludge-resistant polycarboxylic acid water-reducing agent.

[0090] Liquid A is a solution prepared from 22g acrylic acid, 8g hydroxyethyl acrylate, 4g quaternary ammonium salt compound B3 and 10g water, and the dropwise addition time of liquid A is 60min;

[0091] Solution B is a solution prepared from 0.2 g of sodium formaldehyde sulfoxylate, 0.22 g of thioglycolic acid and 42 g of water, and the addition time is 80 min.

[0092] Example 4

[0093] 90 g of allyl-terminated polyether monomer A1, 90 g of ethylene glycol monovinyl polyethylene glycol ether and 300 g of water were placed in a four-necked flask, stirred and dissolved, and then 0.01 g of ferrous sulfate and 1.5 g of hydrogen peroxide were added to obtain a base solution;

[0094] Adjust the reaction temperature to 20-35°C. Add liquid A and liquid B to the four-necked flask at the same time, keep warm for 1.5 hours after the addition, then add liquid alkali to neutralize and obtain the mud-blocking polycarboxylate water-reducing agent.

[0095] Liquid A is a solution prepared from 22g acrylic acid, 8g hydroxyethyl acrylate, 4g quaternary ammonium salt compound B3 and 10g water, and the dropwise addition time of liquid A is 70min;

[0096] Liquid B is composed of 0.2 g sodium formaldehyde sulfoxylate, 0.22 g thioglycolic acid and 42 g water, and the addition time is 60 to 80 min.

[0097] Comparative Example 1

[0098] The difference from Example 1 is that the allyl-terminated polyether monomer A1 is replaced by an equal amount of 4-hydroxybutyl vinyl polyoxyethylene ether.

[0099] Comparative Example 2

[0100] The difference from Example 1 is that no quaternary ammonium salt compound is added, and the amount of water is adjusted so that the solid content of the mud-blocking polycarboxylate water-reducing agent prepared is the same as that in Example 1.

[0101] Comparative Example 3

[0102] Commercially available water reducing agent KZJ-Point 400S.

[0103] The polycarboxylate water-reducing agent samples synthesized in Examples 1-4 and Comparative Examples 1-2 were compared with the commercially available polycarboxylate water-reducing agent in Comparative Example 3 to test the initial slump and expansion of concrete as well as the slump and expansion over time according to GB 8076-2008 "Concrete Admixtures" and GB / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures". The concrete mix ratio is: cement (Chunchi P·O 42.5R) 360kg / m 3 、Mechanical sand 860kg / m 3 , Stone (5~20mm) 1000kg / m 3 、Water 172kg / m 3 The results obtained by using montmorillonite (replacing cement according to the actual replacement ratio) are shown in Table 1.

[0104] Table 1 Concrete performance test results

[0105]

[0106] From the results in Table 1, it can be seen that in Comparative Example 3, as the dosage increases, the initial expansion changes greatly. When the dosage is small, the basic fluidity is poor, and water seepage is likely to occur when the dosage increases, and the sensitive width to the dosage is small; while the polycarboxylate water-reducing agent synthesized by the embodiment and comparative examples 1-2 has a small change in expansion as the dosage increases, and a large sensitive width to the dosage, that is, it is less sensitive to the dosage.

[0107] At the same dosage, when montmorillonite is added, it can be found that the polycarboxylate water-reducing agent synthesized in the embodiment and the comparative example has little effect on the initial expansion and the expansion over time, while the comparative example 3 has a large loss, indicating that the polycarboxylate water-reducing agent synthesized in the invention has good mud resistance and better dispersibility. The polycarboxylate water-reducing agent prepared by the present invention has low sensitivity to the dosage of the water-reducing agent, mud resistance, can improve the workability of concrete, has no adverse effects, is widely applicable, is fast to prepare and has high efficiency.

[0108] It should be noted that the specific parameters or some reagents in the above embodiments are specific embodiments or preferred embodiments of the present invention, rather than limiting the present invention; those skilled in the art can make adaptive adjustments within the scope of the present invention.

Claims

1. A mud-blocking polycarboxylate water-reducing agent, characterized in that: The raw materials for preparing the mud-blocking polycarboxylate water-reducing agent include, by weight: The raw materials for preparing the allyl-terminated polyether monomer include unsaturated alcohol, allyl compound and alkaline catalyst.

2. The sludge-blocking polycarboxylate water-reducing agent according to claim 1, characterized in that: The allyl-terminated polyether monomer structural formula is as follows: Wherein, R1 is CH3-, CH3CH2- or (CH3)2CH-; R2 is CH3-, CH3CH2- or (CH3)2CH-; R3 is CH3-, CH3CH2- or (CH3)2CH-.

3. The anti-sludge polycarboxylate water reducer according to claim 1, characterized in that: The allyl compound includes at least one of allyl chloride and allyl bromide.

4. The anti-sludge polycarboxylate water reducer according to claim 1, characterized in that: The alkaline catalyst includes at least one of potassium hydroxide, sodium hydroxide and triethanolamine.

5. The anti-sludge polycarboxylate water reducer according to claim 1, characterized in that: The raw materials for preparing the allyl-terminated polyether monomer also include phosphoric acid, and the weight ratio of the unsaturated alcohol, the allyl chloride compound, the alkaline catalyst and the phosphoric acid is (18-20): (4-8): (8-12): (0.3-0.6).

6. The anti-sludge polycarboxylate water reducer according to claim 1, characterized in that: The structural formula of the quaternary ammonium salt compound is as follows: One of them.

7. The anti-sludge polycarboxylate water reducer according to claim 1, characterized in that: In terms of weight parts, the raw materials for preparing the mud-blocking polycarboxylate water-reducing agent include:

8. A method for preparing the mud-blocking polycarboxylate water-reducing agent according to any one of claims 1 to 7, characterized in that: Includes steps: The allyl-terminated polyether monomer, the oxidant and water are stirred evenly to completely dissolve them to obtain a base solution; Add liquid A and liquid B dropwise to the base liquid, and after the addition is completed, continue to keep warm and react for 1h to 2h to obtain the sludge-blocking polycarboxylate water-reducing agent; Wherein, the liquid A is an aqueous solution of an unsaturated acid monomer, an unsaturated ester monomer and a quaternary ammonium salt compound; Liquid B is an aqueous solution of a reducing agent and a chain transfer agent.

9. The method for preparing the mud-blocking polycarboxylate water-reducing agent according to claim 8, characterized in that: The preparation method of the allyl-terminated polyether monomer comprises the steps of: adding a basic catalyst to an unsaturated alcohol to obtain a first mixture; In a water bath maintained at 55° C. to 65° C., the allyl compound is added dropwise to the first mixture, and the mixture is stirred at a constant temperature for 4 to 6 hours. After the addition is completed, the reaction is continued at a constant temperature for 1 to 2 hours to obtain the allyl-terminated polyether monomer.

10. The method for preparing the mud-blocking polycarboxylate water-reducing agent according to claim 8, characterized in that: The preparation method of the quaternary ammonium salt compound monomer comprises the steps of: dissolving dopamine in an acidic solution to obtain a dopamine solution; dissolving an aldehyde compound in an alcohol solution to obtain an aldehyde compound solution; Adding an aldehyde compound solution to the dopamine solution, stirring for 18 h to 24 h, and adjusting the pH value to neutral to obtain compound A; In a water bath at 55°C to 65°C, the compound A is dissolved in an alcohol solution, a base is added, and after reacting for 3h to 5h, a 3-chloro-2-hydroxypropyltrimethylammonium chloride solution is added dropwise, and the reaction is continued for 4h to 5h to obtain a quaternary ammonium salt compound.

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