EPEG type polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention relates to the technical field of concrete admixtures, in particular to an EPEG type polycarboxylate superplasticizer and a preparation method thereof. The EPEG type polycarboxylate superplasticizer is prepared by copolymerization reaction of ethylene glycol monovinyl polyglycol ether, first unsaturated carboxylic acid and a functional monomer XS under the action of an initiator and a chain transfer agent. The EPEG type polycarboxylic acid water reducing agent provided by the invention has the advantages of excellent water reducing effect and good adaptability. A normal-temperature free radical solution copolymerization synthesis technology is adopted for synthesis, heating is not needed in the preparation process, preparation steps are simple and convenient, raw materials are easy to obtain, equipment is conventional, and actual industrial application requirements can be met.

Description

Technical Field

[0001] The present application relates to the technical field of concrete admixtures, and in particular to an EPEG type polycarboxylate water reducer and a preparation method thereof. Background Art

[0002] With the development of the times, the infrastructure construction at home and abroad has gradually increased, the amount of engineering projects has continued to expand, and the demand for various raw materials and admixtures of cement concrete used in engineering projects has also continued to increase. As a high-performance concrete admixture, polycarboxylate water reducer has been widely used in the construction industry for its excellent water-reducing effect and good adaptability.

[0003] As a high-performance concrete admixture, polycarboxylate water-reducing agent is widely used in the construction industry for its excellent water-reducing effect and good adaptability. However, under certain specific conditions, such as poor quality of sand and gravel in the raw materials and high mud content, traditional polycarboxylate water-reducing agent is prone to problems such as high dosage requirements and poor aggregate adaptability, and its adaptability still needs to be improved.

[0004] In recent years, EPEG (ethylene glycol monovinyl polyethylene glycol ether) as a new type of polyether macromonomer for synthesizing polycarboxylic acid water reducers has shown better water reduction effect and better adaptability than other types of polyether macromonomers for synthesizing polycarboxylic acid water reducers due to its unique molecular structure and reactivity. However, the adaptability improvement effect of existing EPEG-type polycarboxylic acid water reducers is still not ideal, and its water reduction effect still needs to be improved.

[0005] Therefore, the development of an EPEG type polycarboxylate water reducer with excellent water-reducing effect and good adaptability is of great significance to the development of the construction industry. Summary of the invention

[0006] In order to solve the problems of the prior art mentioned in the above background technology, the present application provides an EPEG type polycarboxylate water reducer, and its technical solution is as follows: The EPEG type polycarboxylate water reducer is prepared by copolymerization of ethylene glycol monovinyl polyethylene glycol ether, a first unsaturated carboxylic acid and a functional monomer XS under the action of an initiator and a chain transfer agent; the structural formula of the functional monomer XS is as follows: ; Wherein, R1 is H or CH3.

[0007] In some embodiments, the preparation process of the functional monomer XS is: adding 3-(3-aminophenoxy)propyltrimethoxysilane and a second unsaturated carboxylic acid into a reactor to form a mixture; wherein the molar ratio of 3-(3-aminophenoxy)propyltrimethoxysilane to the second unsaturated carboxylic acid is (1.0-1.2):1; adding an organic solvent to the mixture under a protective atmosphere, and adding a catalyst; under the action of the catalyst, heating to 40-60°C to react for 3-6 hours, and finally filtering the reaction solution in turn, removing the organic solvent, to obtain the functional monomer XS.

[0008] It should be noted that the amount of organic solvent used is based on the ability of 3-(3-aminophenoxy)propyltrimethoxysilane and the second unsaturated carboxylic acid to disperse in the solvent and react. Since the solvent will be removed by rotary evaporation later, there is no excessive restriction on the amount of organic solvent used.

[0009] In some embodiments, the second unsaturated carboxylic acid is at least one of acrylic acid and methacrylic acid.

[0010] In some embodiments, the organic solvent is at least one of dichloromethane, chloroform, methyl acetate, and tetrahydrofuran.

[0011] In some embodiments, the catalyst is at least one of 4-dimethylaminopyridine (DMAP), dicyclohexylcarbodiimide (DCC), pyridine, and imidazole.

[0012] In some embodiments, the protective atmosphere is N2 atmosphere; In some embodiments, the reaction solution is filtered to obtain a filtrate, and then the filtrate is subjected to rotary evaporation to remove the organic solvent to obtain the functional monomer XS.

[0013] In some embodiments, under the action of an initiator and a chain transfer agent, the ethylene glycol monovinyl polyethylene glycol ether, the first unsaturated carboxylic acid, and the functional monomer XS are copolymerized to prepare an EPEG type polycarboxylic acid water reducer; wherein the copolymerization reaction temperature is 15 to 35° C.; and the weight ratio of the ethylene glycol monovinyl polyethylene glycol ether, the first unsaturated carboxylic acid, and the functional monomer XS is 200: (6 to 12): (8 to 16).

[0014] In some embodiments, the initiator is composed of a reducing agent and an oxidizing agent; the copolymerization process is: dissolving the ethylene glycol monovinyl polyethylene glycol ether in a certain amount of water; controlling the temperature of the reaction system at 15-35°C, and then adding an oxidizing agent and stirring evenly; then maintaining the temperature of the reaction system at 15-35°C, adding liquid A and liquid B for constant temperature reaction; after the addition is completed, keeping the reaction system temperature at 15-35°C for 0.5-1h; finally, adding a neutralizing agent to adjust the pH to 5.5-6.5 to obtain the EPEG type polycarboxylic acid water reducer; wherein, after the functional monomer XS, the first unsaturated carboxylic acid and a portion of water are evenly mixed, the liquid A is obtained; after the chain transfer agent, the reducing agent and a portion of water are evenly mixed, the liquid B is obtained.

[0015] In some embodiments, the liquid A and the liquid B are added dropwise for 0.5 to 2 hours.

[0016] In some embodiments, the raw material formula of the copolymerization reaction is, by weight: 200 parts of ethylene glycol monovinyl polyethylene glycol ether, 8 to 16 parts of functional monomer XS, 6 to 12 parts of the first unsaturated carboxylic acid, 0.5 to 2.0 parts of oxidant, 0.1 to 0.5 parts of reducing agent, 0.4 to 1.4 parts of chain transfer agent, and 196 to 218 parts of water in total.

[0017] In some embodiments, the molecular weight of the ethylene glycol monovinyl polyethylene glycol ether is 1500-3000.

[0018] In some embodiments, the first unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, and maleic anhydride.

[0019] In some embodiments, the oxidant is at least one of a 27.5% mass concentration hydrogen peroxide solution, ammonium persulfate, and sodium persulfate.

[0020] In some embodiments, the chain transfer agent is at least one of sodium hypophosphite, thioglycolic acid, and mercaptopropionic acid.

[0021] In some embodiments, the reducing agent is at least one of ascorbic acid, Bruggolite FF6, and Bruggolite E01.

[0022] In some embodiments, the neutralizing agent is a sodium hydroxide solution with a mass concentration of 32%.

[0023] The present application also provides a method for preparing the EPEG type polycarboxylate water reducer as described above, wherein the initiator comprises an oxidant and a reducing agent; the preparation method comprises the following preparation steps: Dissolving the ethylene glycol monovinyl polyglycol ether in a certain amount of water, controlling the temperature of the reaction system at 15 to 35° C., and then adding an oxidant and stirring evenly to form a mixed solution; The functional monomer XS, the first unsaturated carboxylic acid and a portion of water are uniformly mixed to obtain liquid A; The chain transfer agent, the reducing agent and a portion of water are uniformly mixed to obtain liquid B; Then, the temperature of the reaction system is maintained at 15 to 35° C., and the solution A and the solution B are added dropwise to the mixed solution for constant temperature reaction, and the adding time is 0.5 to 2 hours; After the dropwise addition is completed, the reaction system is kept at a temperature of 15 to 35° C. for 0.5 to 1 h, and finally a neutralizing agent is added to adjust the pH to 5.5 to 6.5 to obtain the EPEG type polycarboxylate water reducer.

[0024] Compared with the existing technology, the EPEG type polycarboxylate water reducer provided in this application has the following beneficial effects: The EPEG type polycarboxylate water reducer provided in the present application has both excellent water reduction effect and good adaptability. It is synthesized by free radical solution copolymerization synthesis technology at room temperature, and the preparation process does not require heating. The preparation steps are simple, the raw materials are easily available, and the equipment is conventional, which can meet the actual industrial application needs. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] The present application also provides the following embodiments and comparative examples: Embodiment 1: Functional monomer XS preparation: (1) Add 148 parts by mass of 3-(3-aminophenoxy)propyltrimethoxysilane and 36 parts by mass of acrylic acid into a reactor. The molar ratio of 3-(3-aminophenoxy)propyltrimethoxysilane to acrylic acid is 1.09:1; (2) Under N2 atmosphere, 500 mL of tetrahydrofuran was added, and the mixture was reacted at 50°C for 4 h under the catalysis of 4-dimethylaminopyridine (DMAP) to obtain a reaction solution; Wherein, the usage of catalyst 4-dimethylaminopyridine is 1.36 parts.

[0027] (3) The reaction solution is filtered and the obtained filtrate is subjected to rotary evaporation to remove the organic solvent, thereby obtaining the functional monomer XS.

[0028] Preparation of EPEG type polycarboxylate water reducer: (1) Add 200 parts of ethylene glycol monovinyl polyglycol ether and 150 parts of water into a three-necked flask, maintain the temperature at 15-35°C, and stir to form a mixed solution; (2) 13.6 parts of functional monomer XS, 10 parts of acrylic acid and 28 parts of water were mixed evenly to prepare liquid A; (3) Mix 0.6 parts of thioglycolic acid, 0.32 parts of ascorbic acid and 32 parts of water to prepare solution B; (4) Add 1.5 parts of 27.5% hydrogen peroxide into the flask and stir evenly; (5) Add the above solution A and solution B dropwise into a three-necked flask respectively, and react at a constant temperature of 15-35°C for 1.5 hours; (6) After the addition is completed, the mixture is kept at 15 to 35° C. for 1 hour, and then a 32% sodium hydroxide solution is added to the three-necked flask to adjust the pH value of the mixed solution to 5.5 to 6.5, thereby obtaining the EPEG type polycarboxylic acid water reducer.

[0029] Embodiment 2: Functional monomer XS preparation: (1) 156 parts by mass of 3-(3-aminophenoxy)propyltrimethoxysilane and 43 parts by mass of methacrylic acid were added to a reactor; wherein the molar ratio of 3-(3-aminophenoxy)propyltrimethoxysilane to methacrylic acid was 1.15:1.

[0030] (2) Under N2 atmosphere, 500 mL of tetrahydrofuran was added, and the mixture was reacted at 54°C for 4 h under the catalysis of 4-dimethylaminopyridine (DMAP) to obtain a reaction solution; Wherein, the usage of catalyst 4-dimethylaminopyridine is 1.45 parts.

[0031] (3) The reaction solution is filtered and the obtained filtrate is subjected to rotary evaporation to remove the organic solvent, thereby obtaining the functional monomer XS.

[0032] Preparation of EPEG type polycarboxylate water reducer: (1) Add 200 parts of ethylene glycol monovinyl polyglycol ether and 150 parts of water into a three-necked flask, maintain the temperature at 15-35°C, and stir to form a mixed solution; (2) 15.6 parts of functional monomer XS, 8 parts of acrylic acid and 30 parts of water were mixed evenly to prepare liquid A; (3) Mix 0.8 parts of sodium hypophosphite, 0.25 parts of Bruggolite FF6 and 30 parts of water to prepare Liquid B; (4) Add 1.3 parts of 27.5% hydrogen peroxide into the flask and stir evenly; (5) Add the above solution A and solution B dropwise into a three-necked flask respectively, and react at a constant temperature of 15-35°C for 1.5 hours; (6) After the addition is completed, the mixture is kept at 15 to 35° C. for 1 hour, and then a 32% sodium hydroxide solution is added to the three-necked flask to adjust the pH value of the mixed solution to 5.5 to 6.5, thereby obtaining the EPEG type polycarboxylic acid water reducer.

[0033] Comparative Example 1: Commercially available EPEG type polycarboxylate water reducer Point-T; Comparative Example 2: (Functional monomer XS is replaced by acrylic acid) The only difference from Example 1 is that the functional monomer XS in Example 1 is replaced by acrylic acid, and the rest is the same as Example 1.

[0034] Comparative Example 3: (Functional monomer XS is replaced by acrylamide) The only difference from Example 1 is that the functional monomer XS in Example 1 is replaced by acrylamide, and the rest is the same as Example 1.

[0035] Comparative Example 4: (Functional monomer XS is replaced by vinyl trimethoxysilane) The only difference from Example 1 is that the functional monomer XS in Example 1 is replaced by vinyltrimethoxysilane, and the rest is the same as Example 1.

[0036] Comparative Example 5: (the ratio of the first unsaturated carboxylic acid and the functional monomer XS is out of the range) The only difference from Example 1 is that during the copolymerization reaction, 200 parts of ethylene glycol monovinyl polyethylene glycol ether, 15 parts of acrylic acid, and 19 parts of functional monomer XS are used. The rest is the same as Example 1.

[0037] Performance test of embodiments and comparative examples: In order to further illustrate the performance effect of the EPEG type polycarboxylate water reducer provided in the present application, according to the standard GB 8076-2008 "Concrete Admixtures", the products prepared in the above embodiments and comparative examples were subjected to cement concrete working performance tests; using the same compounding conditions, the water reducer dosage was 0.18%, the concrete mix ratio was shown in Table 1, and the concrete performance test results were shown in Table 2: Table 1 Concrete mix ratio Unit: kg / m3 cement Fly ash (grade II) Mineral powder (S95) Machine-made sand (MB=2.2) gravel water 2.9 0.4 0.3 9.2 9.5 1.6 Among them, MB of machine-made sand is 2.2, indicating that the quality of machine-made sand in concrete is poor, and concrete is prepared by using poor raw materials, which is used to reflect the good adaptability of the polycarboxylate water-reducing agent of the present application.

[0038] Table 2 Concrete working performance test

[0039] The experimental results show that: Under the condition of equal dosage, the polycarboxylate water-reducing agent of the embodiment prepared in the present application has better water-reducing effect and adaptability than comparative examples 1 to 5.

[0040] In Comparative Example 1, the existing EPEG polycarboxylate water-reducing agent has poor water-reducing effect, poor concrete state, low compressive strength and poor adaptability.

[0041] In Comparative Example 2, after the functional monomer XS was replaced with acrylic acid, the water reduction effect was poor, the concrete state was poor, the compressive strength was low, and the adaptability was poor.

[0042] In Comparative Example 3, after the functional monomer XS was replaced with acrylamide, the water reduction effect was significantly reduced, the concrete state was average, and the adaptability was poor.

[0043] In Comparative Example 4, after the functional monomer XS was replaced with vinyltrimethoxysilane, the loss over time was significantly accelerated, the concrete state was average, and the adaptability was poor.

[0044] In Comparative Example 5, the amount of the first unsaturated carboxylic acid and the functional monomer XS exceeds the amount recommended by the technical solution. The unbalanced monomer ratio is likely to affect the polymerization process, thereby causing changes in the molecular weight and distribution of the polymer. At the same time, the hydrophobicity and hydrophilicity of the polymer chain segment are unbalanced, affecting the stability and dispersibility of the polymer, which is not conducive to the free distribution of the water reducer molecules on the cement particles, and the water reduction effect is significantly reduced.

[0045] In summary, the EPEG type polycarboxylate water reducer provided in the present application has at least the following design concepts and beneficial effects: 1. The EPEG type polycarboxylic acid water reducer provided in the present application has an excellent water-reducing effect, which is due to the fact that the research and development process effectively improves the adsorption and dispersion performance of the water reducer in the cement environment. The alkoxy groups of silane in the water reducer molecules are hydrolyzed to produce silanol groups, which produce chemical adsorption on the surface of cement particles to form a stable film, which reduces the interaction between cement particles and reduces the viscosity and yield stress of cement paste. At the same time, the rigid hydrophobic structure of the benzene ring can reduce the hydrogen bonding between the EPEG polyether side chain and the montmorillonite layer, and the steric hindrance effect further prevents the aggregation and sedimentation of cement particles, and releases the encapsulated free water, which increases the fluidity of concrete.

[0046] 2. The EPEG type polycarboxylic acid water-reducing agent provided in this application has good adaptability, because the amide group in the introduced functional monomer XS slowly hydrolyzes in the alkaline environment of concrete to release more carboxylic acid groups, ensuring the good fluidity of the concrete. At the same time, the amide group can accelerate the dissolution of tricalcium silicate and the crystal precipitation of hydration products, thereby improving the early strength of concrete. Silane can improve the pore structure of concrete, reduce the penetration and erosion of harmful substances, and improve the durability of concrete.

[0047] 3. The EPEG type polycarboxylate water reducer provided in the present application is formed by introducing a functional monomer XS and copolymerizing with ethylene glycol monovinyl polyethylene glycol ether and a first unsaturated carboxylic acid, wherein the copolymerized monomers act synergistically with each other, rather than simply superimposing functions, and the structural selection and proportion design of each monomer will affect the structure of the final polycarboxylate water reducer, thereby affecting its performance and effect. For example, if the proportion of ethylene glycol monovinyl polyethylene glycol ether, the functional monomer XS and the first unsaturated carboxylic acid is not within the scope of the present application, the molecular structure of the polycarboxylate water reducer does not conform to the expected design, and the water reduction effect is poor.

[0048] 4. The EPEG type polycarboxylic acid water reducer provided in the present application, by introducing functional monomer XS, introduces silane alkoxy, amide and other groups that play a corresponding role in the water reducer. However, it is not possible to achieve the effect of the present application simply by introducing the corresponding silane alkoxy and amide groups in the water reducer molecule. How to introduce silane alkoxy, amide and other groups (whether different groups are introduced through copolymerization of different monomers, or multiple groups are integrated into a functional monomer to participate in the polymerization introduction, the two methods are different), and the specific structure of the functional monomer that integrates silane alkoxy and amide groups for participating in the polymerization, will result in different side chain structures of the obtained polycarboxylic acid water reducer, thereby resulting in different structural molecules of the water reducer, which ultimately affects its performance and effect.

[0049] The present application adopts a functional monomer XS with integrated alkoxy, amide and other groups of a specific structure, and then introduces the functional monomer XS with a specific structure into the side chain of the polycarboxylic acid water reducer through a copolymerization reaction, so as to obtain the desired polycarboxylic acid water reducer structure and achieve the desired effect of the present application.

[0050] If an unsaturated amide monomer containing an amide group and an alkoxy-containing silane monomer are respectively used as comonomers to copolymerize with monomers such as ethylene glycol monovinyl polyethylene glycol ether and an unsaturated carboxylic acid monomer, the monomers with different groups cause competitive reactions due to differences in reaction activity and solubility, and the side chain of the polycarboxylic acid has a structure in which the groups are unevenly distributed, which is different from the structure in which the groups are evenly distributed in the side chain of the present application. Therefore, the structure of the obtained polycarboxylic acid water reducer is different, and this solution cannot achieve the effect of the present application.

[0051] For example, the solution disclosed in patent publication number CN116041630A is to prepare EPEG polycarboxylic acid water reducer by copolymerizing ethylene glycol monovinyl polyethylene glycol ether, unsaturated amide monomer, unsaturated carboxylic acid monomer, unsaturated sulfonate, silane monomer, dimethyl chloride allyl phosphate and quaternary ammonium salt polyether ester monomer at 10°C to 15°C. This solution does not provide corresponding proof of the adaptability effect of the water reducer. It can be seen from its test results that it has good water reducing performance in conventional raw material formulas.

[0052] 5. The EPEG type polycarboxylic acid water reducer provided in this application has excellent compatibility with polycarboxylic acid molecules, supports independent use or compound application with conventional water reducers, and has significant market potential.

[0053] 6. The EPEG type polycarboxylate water reducer provided in the present application can be prepared at room temperature, the process is simple and mild, no complicated temperature control steps are required, the energy consumption is low, and it has efficient production and practical value.

[0054] In summary, the present application introduces unsaturated amide phenyl silane functional monomer XS, and can cooperate with some common unsaturated carboxylic acids, adopts room temperature free radical solution copolymerization synthesis technology, and does not require heating to prepare an EPEG type polycarboxylic acid water reducer with excellent water reduction effect, good adaptability and the ability to meet the needs of actual industrial applications.

[0055] It should be noted that: EPEG is the abbreviation for ethylene glycol monovinyl polyethylene glycol ether.

[0056] In this article, “~” is used to indicate a numerical range, and the range indicated by this expression includes two endpoint values.

[0057] In addition to the actual selections embodied in the above specific embodiments, the above formulation ranges may be used in the specific implementation of the present application, including but not limited to the above embodiment schemes.

[0058] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments of the present application, but are not intended to limit the present application. Those skilled in the art may make adaptive adjustments within the scope of the present application.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An EPEG type polycarboxylate water reducer, characterized in that: It is prepared by copolymerization of ethylene glycol monovinyl polyethylene glycol ether, the first unsaturated carboxylic acid and the functional monomer XS under the action of an initiator and a chain transfer agent; The structural formula of the functional monomer XS is as follows: ； Wherein, R1 is H or CH3.

2. The EPEG type polycarboxylate water reducer according to claim 1, characterized in that: The preparation process of the functional monomer XS is as follows: Add 3-(3-aminophenoxy)propyltrimethoxysilane and a second unsaturated carboxylic acid to a reactor to form a mixture; wherein the molar ratio of 3-(3-aminophenoxy)propyltrimethoxysilane to the second unsaturated carboxylic acid is (1.0 to 1.2): 1; An organic solvent and a catalyst are added to the mixture under a protective atmosphere; the mixture is heated to 40 to 60° C. and reacted for 3 to 6 hours under the action of the catalyst; and the reaction liquid is filtered and the organic solvent is removed in sequence to obtain the functional monomer XS.

3. The EPEG type polycarboxylate water reducer according to claim 2, characterized in that: The second unsaturated carboxylic acid is at least one of acrylic acid and methacrylic acid; The organic solvent is at least one of dichloromethane, chloroform, methyl acetate and tetrahydrofuran; The catalyst is at least one of 4-dimethylaminopyridine, dicyclohexylcarbodiimide, pyridine and imidazole.

4. The EPEG type polycarboxylate water reducer according to claim 2, characterized in that: The protective atmosphere is N2 atmosphere; The reaction solution is filtered to obtain a filtrate, and then the filtrate is subjected to rotary evaporation to remove the organic solvent to obtain the functional monomer XS.

5. The EPEG type polycarboxylate water reducer according to claim 1, characterized in that: Under the action of an initiator and a chain transfer agent, the ethylene glycol monovinyl polyethylene glycol ether, the first unsaturated carboxylic acid, and the functional monomer XS are copolymerized to obtain an EPEG type polycarboxylic acid water reducer; Wherein, the copolymerization reaction temperature is 15-35° C.; the weight ratio of the ethylene glycol monovinyl polyethylene glycol ether, the first unsaturated carboxylic acid, and the functional monomer XS is 200: (6-12): (8-16).

6. The EPEG type polycarboxylate water reducer according to claim 1, characterized in that: The initiator is composed of a reducing agent and an oxidizing agent; the copolymerization process is: The ethylene glycol monovinyl polyethylene glycol ether is dissolved in a certain amount of water; the temperature of the reaction system is controlled at 15 to 35° C., and then an oxidant is added and stirred evenly; then the temperature of the reaction system is maintained at 15 to 35° C., and liquid A and liquid B are added for constant temperature reaction; after the addition is completed, the reaction system is kept warm at 15 to 35° C. for 0.5 to 1 hour; finally, a neutralizing agent is added to adjust the pH to 5.5 to 6.5 to obtain the EPEG type polycarboxylic acid water reducer; The functional monomer XS, the first unsaturated carboxylic acid and a portion of water are uniformly mixed to obtain the liquid A; the chain transfer agent, the reducing agent and a portion of water are uniformly mixed to obtain the liquid B.

7. The EPEG type polycarboxylate water reducer according to claim 6, characterized in that: The A solution and the B solution are added dropwise for 0.5 to 2 hours; The raw material formula of the copolymerization reaction is as follows by weight: 200 parts of ethylene glycol monovinyl polyethylene glycol ether, 8 to 16 parts of functional monomer XS, 6 to 12 parts of the first unsaturated carboxylic acid, 0.5 to 2.0 parts of oxidant, 0.1 to 0.5 parts of reducing agent, 0.4 to 1.4 parts of chain transfer agent, and 196 to 218 parts of water in total.

8. The EPEG type polycarboxylate water reducer according to claim 1, characterized in that: The molecular weight of the ethylene glycol monovinyl polyethylene glycol ether is 1500 to 3000; The first unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, and maleic anhydride.

9. The EPEG type polycarboxylate water reducer according to claim 6, characterized in that: The oxidant is at least one of a 27.5% mass concentration hydrogen peroxide solution, ammonium persulfate, and sodium persulfate; The chain transfer agent is at least one of sodium hypophosphite, thioglycolic acid, and mercaptopropionic acid; The reducing agent is at least one of ascorbic acid, Bruggolite FF6, and Bruggolite E01; The neutralizing agent is a sodium hydroxide solution with a mass concentration of 32%.

10. A method for preparing the EPEG type polycarboxylate water reducer according to any one of claims 1 to 9, characterized in that: The initiator comprises an oxidant and a reductant; and the preparation method comprises the following preparation steps: Dissolving the ethylene glycol monovinyl polyglycol ether in a certain amount of water, controlling the temperature of the reaction system at 15 to 35° C., and then adding an oxidant and stirring evenly to form a mixed solution; The functional monomer XS, the first unsaturated carboxylic acid and a portion of water are uniformly mixed to obtain liquid A; The chain transfer agent, the reducing agent and a portion of water are uniformly mixed to obtain liquid B; Then, the temperature of the reaction system is maintained at 15 to 35° C., and the solution A and the solution B are added dropwise to the mixed solution for constant temperature reaction, and the adding time is 0.5 to 2 hours; After the dropwise addition is completed, the reaction system is kept at a temperature of 15 to 35° C. for 0.5 to 1 h, and finally a neutralizing agent is added to adjust the pH to 5.5 to 6.5 to obtain the EPEG type polycarboxylate water reducer.

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