Viscosity reduction type polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention provides a viscosity reduction type polycarboxylic acid water reducing agent and a preparation method thereof, and belongs to the technical field of water reducing agents. The viscosity reduction type polycarboxylate superplasticizer provided by the invention can remarkably improve the construction and working performance of high-performance concrete, effectively reduce the viscosity of a concrete mixture, and improve the fluidity and homogeneity of the concrete mixture, so that smooth pumping construction is guaranteed; meanwhile, the water reducing agent can stably control the gas content of the concrete on the premise of improving the workability, ensures that the concrete has good compactness and microstructure after being hardened, and finally achieves the comprehensive effect of improving the mechanical strength and long-term durability of the concrete; in addition, the preparation process conditions are mild, a high-temperature and high-pressure environment is not needed, the production process is simplified, energy consumption and production cost can be reduced, and good economical efficiency and large-scale application prospects are achieved.

Description

Technical Field

[0001] This invention relates to the field of water-reducing agent technology, and in particular to a viscosity-reducing polycarboxylate water-reducing agent and its preparation method. Background Technology

[0002] Polycarboxylate superplasticizers are the third generation of high-performance superplasticizers developed after lignin sulfonate and naphthalene sulfonate superplasticizers, and have become an indispensable key chemical admixture in modern concrete technology. Their molecular structure is typically designed as a "comb," with anionic groups such as carboxyl and sulfonic acid groups attached to the main chain. These groups act on cement particles through electrostatic repulsion. Simultaneously, the long polyether side chains create a steric hindrance effect between cement particles, collectively playing a crucial role in dispersing cement particles, releasing encapsulated water, thereby reducing mixing water consumption or improving concrete fluidity.

[0003] As the construction industry moves towards high-rise buildings and large-span structures, the performance requirements for concrete are increasing, leading to the widespread application of high-strength, high-performance concrete with low water-cement ratios. However, while low water-cement ratios result in high strength, they also cause a sharp increase in the viscosity of the concrete mixture, leading to poor flowability and high resistance, which seriously affects the efficiency of concrete pumping and the final quality of the poured components. To address the high viscosity problem, modifying the molecular structure of polycarboxylate superplasticizers is a major approach in existing technologies. For example, introducing different functional groups and adjusting the length and density of side chains can achieve better viscosity reduction while maintaining high dispersibility.

[0004] Despite this, conventional polycarboxylate superplasticizers still face several challenges in application. Some products have limited effectiveness in reducing viscosity, making it difficult to meet the construction requirements under extremely low water-cement ratio conditions; some superplasticizers introduce excessive or unstable air bubbles during preparation or use, which, while potentially temporarily increasing the volume of the paste, can impair the final strength and durability of the concrete; furthermore, modern concrete often incorporates mineral admixtures such as fly ash, mineral powder, and silica fume, and the compatibility (compatibility) between superplasticizers and these different types and qualities of admixtures can lead to poor concrete workability or abnormally increased viscosity. Therefore, developing a novel polycarboxylate superplasticizer that can effectively reduce concrete viscosity, has good compatibility with cementitious material systems, exhibits stable performance, and is easy to industrially produce has been a technical problem that those skilled in the art have been striving to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a viscosity-reducing polycarboxylate superplasticizer and its preparation method, which provides an effective means for the prior art.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a viscosity-reducing polycarboxylate superplasticizer, which is prepared by copolymerization of the following raw materials in parts by weight: 350-380 parts of polyether macromonomer, 20-30 parts of acrylic acid, 15-25 parts of methacrylic tartaric acid, 8-12 parts of sodium methallyl sulfonate, 2-4 parts of chain transfer agent, 1.5-3 parts of oxidant, 0.8-1.5 parts of reducing agent, and 400-450 parts of deionized water; The polyether macromonomer is an EPEG-type polyether macromonomer.

[0007] Preferably, the chain transfer agent is selected from one of mercaptoethanol, mercaptopropionic acid, or dodecyl mercaptan.

[0008] Preferably, the oxidant is selected from either ammonium persulfate or potassium persulfate.

[0009] Preferably, the reducing agent is selected from sodium sulfite, sodium metabisulfite, or sodium ascorbate.

[0010] This invention also provides a method for preparing the above-mentioned viscosity-reducing polycarboxylate superplasticizer, comprising the following steps: S1. Preparation of base solution: Add the polyether macromonomer to deionized water and stir at 30~35℃ until completely dissolved to obtain the synthesis base solution; S2. Preparation of premixed solution: Dissolve acrylic acid, methacryl tartaric acid and sodium methyl allyl sulfonate in deionized water to obtain solution A; dissolve chain transfer agent and reducing agent in deionized water to obtain solution B; S3. Copolymerization reaction: Add an oxidant to the synthesis base solution and stir to mix well. Then, add solution A and solution B dropwise simultaneously. After the addition is complete, keep the reaction at 30~35℃. Then, adjust the pH value to 7~8 with alkaline solution to obtain the viscosity-reducing polycarboxylate superplasticizer.

[0011] Preferably, in step S1, the solution is stirred until the transmittance is ≥95%.

[0012] Preferably, in step S3, after adding the oxidant, the mixture is stirred at a speed of 300-350 rpm.

[0013] Preferably, in step S3, the heat preservation reaction time is 40~100 min.

[0014] Preferably, in step S3, the alkaline solution is a 30% (w / w) sodium hydroxide aqueous solution.

[0015] The present invention also provides the application of the above-mentioned viscosity-reducing polycarboxylate superplasticizer or the viscosity-reducing polycarboxylate superplasticizer prepared by the above preparation method in the preparation of concrete.

[0016] The technical effects and advantages of this invention are as follows: The viscosity-reducing polycarboxylate superplasticizer and its preparation method provided by this invention can significantly improve the construction and workability of high-performance concrete, effectively reduce the viscosity of concrete mixtures, and improve their fluidity and homogeneity, thereby ensuring smooth pumping construction. At the same time, the superplasticizer can stably control the air content of concrete while improving workability, ensuring that it has good density and microstructure after hardening, ultimately achieving a comprehensive effect of improving the mechanical strength and long-term durability of concrete. In addition, its preparation process is mild, does not require a high-temperature and high-pressure environment, simplifies the production process, and helps to reduce energy consumption and production costs, thus possessing good economic benefits and prospects for large-scale application. Detailed Implementation

[0017] This invention provides a viscosity-reducing polycarboxylate superplasticizer, which is prepared by copolymerization of the following raw materials in parts by weight: 350-380 parts of polyether macromonomer, 20-30 parts of acrylic acid, 15-25 parts of methacrylic tartaric acid, 8-12 parts of sodium methyl allyl sulfonate, 2-4 parts of chain transfer agent, 1.5-3 parts of oxidant, 0.8-1.5 parts of reducing agent, and 400-450 parts of deionized water.

[0018] In the fields of chemical engineering and polymer synthesis, polyether macromonomers generally refer to a class of compounds whose molecular structure contains long polyether chains (mainly polyoxyethylene ether segments) and terminal double bonds (such as allyl, methylallyl, isopentenyl, etc.) that can participate in polymerization reactions. These macromonomers are key starting materials for the synthesis of polycarboxylate-based high-performance water-reducing agents, and the length and structure of their polyether side chains directly affect the performance of the final water-reducing agent product. EPEG (ethylallyl polyethylene glycol ether) is a common type of polyether macromonomer, readily available from various chemical companies on the market.

[0019] Acrylic acid, with the chemical formula CH2=CH-COOH, is a colorless liquid with a pungent odor at room temperature and is miscible with water. It is an important organic chemical raw material and monomer for synthetic resins, widely used in the synthesis of acrylates, superabsorbent resins, flocculants, coatings, and adhesives. In polymer synthesis, the vinyl groups in its molecule can be used in free radical polymerization reactions.

[0020] Methpropenyl tartaric acid is an organic compound containing unsaturated double bonds and multiple carboxyl groups. Tartaric acid is a natural hydroxycarboxylic acid widely found in many fruits. Methpropenyl tartaric acid can be considered a derivative of tartaric acid, with polymerizable methpropenyl groups introduced through reactions such as esterification or etherification. These functional monomers are commonly used in polymer modification.

[0021] Sodium methyl allyl sulfonate is an anionic olefin monomer, a white crystalline or powdery substance, readily soluble in water. Its molecular structure contains sulfonic acid groups and polymerizable double bonds. Due to their excellent water solubility and strong ionization, sulfonate monomers are often incorporated into polymer chains to provide electrostatic repulsion or improve hydrophilicity, and are widely used in water treatment agents, dye dispersants, oilfield chemicals, and cement admixtures.

[0022] Chain transfer agents are compounds that, in free radical polymerization, react with the free radicals of growing polymer chains, terminating their growth while simultaneously generating a new free radical, which can then initiate further monomer polymerization. Commonly used chain transfer agents include sulfur-containing compounds (such as various thiols) and certain halogenated hydrocarbons. Mercaptoethanol, mercaptopropionic acid, and dodecyl mercaptoethanol are common thiol chain transfer agents and are commercially available. They regulate the molecular weight and distribution of the polymer by controlling the length of the molecular chain.

[0023] In chemistry, an oxidizing agent is a substance that gains electrons in a redox reaction. In polymer synthesis, oxidizing agents are often paired with reducing agents to form a redox initiation system, used to generate free radicals at room temperature or lower temperatures to initiate monomer polymerization. Ammonium persulfate and potassium persulfate are peroxyacid salts and commonly used water-soluble oxidizing agents and free radical initiators, widely applied in processes such as emulsion polymerization and aqueous solution polymerization.

[0024] A reducing agent, as opposed to an oxidizing agent, is a substance that loses electrons in a redox reaction. In redox initiation systems, reducing agents are used to undergo electron transfer reactions with oxidizing agents at low temperatures, efficiently generating primary free radicals. Sodium sulfite and sodium metabisulfite are common inorganic sulfite reducing agents; sodium ascorbate, the sodium salt of vitamin C, is also a mild organic reducing agent. All of these can be used to construct low-temperature polymerization initiation systems.

[0025] Deionized water refers to pure water after impurities in ionic form have been removed. It can be produced through methods such as ion exchange and electrodialysis. In fields such as chemical synthesis, biomedicine, and laboratory analysis, deionized water is widely used as a solvent, reaction medium, or cleaning agent to prevent impurity ions in the water from interfering with chemical reactions or product performance.

[0026] This invention also provides a method for preparing the above-mentioned viscosity-reducing polycarboxylate superplasticizer. The method mainly includes three core steps: preparation of the base liquid, preparation of the premixed solution, and copolymerization reaction. This method features mild process conditions, simple operation, and is easy to industrialize.

[0027] Specifically, the preparation method includes the following steps: S1. Preparation of the base solution: Add the prescribed amount of polyether macromonomer to most of the deionized water, control the system temperature within a low range of 30~35℃, and stir until the macromonomer is completely dissolved to form a homogeneous and clear synthesis base solution. Preferably, stir until the solution transmittance is ≥95%, which serves as a direct indicator of complete dissolution and ensures that the subsequent polymerization reaction proceeds smoothly in a homogeneous system.

[0028] S2. Preparation of Premixed Solution: This step aims to pre-prepare a portion of the raw materials into a solution, facilitating precise and uniform subsequent dropwise addition and thus better controlling the polymerization process. Acrylic acid, methacryl tartaric acid, and sodium methyl allyl sulfonate are dissolved in a portion of deionized water in a specific ratio and thoroughly mixed to obtain solution A. Simultaneously, the chain transfer agent and reducing agent are dissolved in the remaining deionized water in a specific ratio and stirred until completely dissolved to obtain solution B. This stepwise preparation method helps avoid prepolymerization or side reactions caused by locally excessively high concentrations of certain components.

[0029] S3. Copolymerization: This is the key step in the synthesis. Add the prescribed amount of oxidant to the synthesis substrate prepared in step S1 and start stirring to ensure uniform mixing. The stirring speed is a crucial factor affecting the mixing effect; preferably, the stirring speed is controlled at 300-350 rpm to ensure uniform dispersion of the oxidant and provide good mass transfer conditions for subsequent dropwise addition. Then, while maintaining stirring and temperature, simultaneously add solutions A and B. The dropwise addition process is crucial for controlling the polymerization reaction smoothly and avoiding explosive polymerization. After the dropwise addition is complete, continue to maintain the reaction temperature within the range of 30-35°C for heat preservation, allowing unreacted monomers to further polymerize and ensuring complete reaction. Preferably, the heat preservation reaction time is 40-100 minutes, which is sufficient to ensure monomer conversion and obtain a stable product. After the heat preservation reaction is completed, stop heating and allow the reaction system to cool naturally or with auxiliary cooling to near room temperature. Finally, adjust the pH of the reaction product to neutral or weakly alkaline (pH 7-8) with an alkaline solution to stabilize product properties and facilitate storage. Preferably, the alkaline solution is a 30% sodium hydroxide aqueous solution, which is easy to operate and has controllable dilution heat.

[0030] This invention also claims protection for the application of the above-mentioned viscosity-reducing polycarboxylate superplasticizer, or the viscosity-reducing polycarboxylate superplasticizer prepared by any of the above-mentioned preparation methods, in the field of building materials, particularly in the preparation of concrete. Adding the superplasticizer of this invention to concrete mixing water can significantly reduce the viscosity of the concrete mixture, improve its workability (such as fluidity), while maintaining good slump retention performance, and has no adverse effect on the strength development of concrete at all ages. It is particularly suitable for preparing high-fluidity, self-compacting, or high-strength, high-performance concrete.

[0031] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1 Raw material components and weight parts of viscosity-reducing polycarboxylate superplasticizer based on molecular structure optimization Raw material composition and weight parts: 350 parts of polyether macromonomer 20 parts acrylic acid 15 parts of methylpropenyl tartaric acid 8 parts of sodium methyl allyl sulfonate 2 parts mercaptoethanol 1.5 parts ammonium persulfate Sodium sulfite 0.8 parts 400 parts deionized water Raw material characteristics description Polyether macromonomer (EPEG): The double bond is directly connected to the oxygen atom, which has high reactivity and a large degree of freedom in the side chain. It can reduce steric resistance, enhance steric hindrance, and improve the dispersion effect on cement particles.

[0033] Methacrylic tartaric acid (MJ): Contains dicarboxyl and methyl hydrophobic groups, which can increase carboxyl density, enhance the adsorption capacity of cement and silica fume, and at the same time regulate the hydrophilic-lipophilic balance (HLB) value to promote the release of free water.

[0034] Sodium methyl allyl sulfonate (SMAS): It provides sulfonic acid groups to enhance electrostatic repulsion and assist in viscosity reduction. The methyl groups it contains can adjust the HLB value. When introduced in appropriate amounts, it can generate microbubbles and reduce the viscosity of cement paste.

[0035] Preparation method Step 1: Setting viscosity reduction targets Target performance parameters: apparent viscosity of cement paste ≤1000MPa•s (when fluidity is 250±10mm); initial fluidity of mortar ≥250mm, retention rate ≥85% after 30min.

[0036] Step 2: Preparation of the base solution Add EPEG to deionized water, control the temperature to 35°C, and stir until completely dissolved (solution transmittance ≥95%) to obtain the synthesis base solution.

[0037] Step 3: Preparation of premixed solution Solution A: Dissolve acrylic acid, methacryl tartaric acid, and sodium methyl allyl sulfonate in deionized water in proportion and stir until homogeneous.

[0038] Solution B: Dissolve the chain transfer agent and reducing agent in deionized water and stir until completely dissolved.

[0039] Step 4: Copolymerization Add the oxidant to the base solution and mix thoroughly at 300-350 rpm. Simultaneously add solution A and solution B dropwise. Solution A dropping time: 60 min, dropping rate: uniform; Solution B addition time: 70 min, added at a uniform rate; After the addition is complete, maintain the temperature at 35℃ for 60 minutes, then cool to room temperature and adjust the pH to 7 with a 30% NaOH aqueous solution to obtain a viscosity-reducing polycarboxylate superplasticizer.

[0040] Performance verification Viscosity reduction effect test: The viscosity reduction effect was verified by measuring the apparent viscosity of cement paste (target ≤1000MPa•s) and the flow time of concrete slump cone (target ≤20s). Dispersion performance test: The initial fluidity of cement mortar is ≥250mm, and the fluidity loss rate after 30 minutes is ≤15%; Strength test: 28-day compressive strength of concrete ≥125MPa (based on the standard mix).

[0041] Example 2 Raw material components and weight parts of viscosity-reducing polycarboxylate superplasticizer based on molecular structure optimization Raw material composition and weight parts: 380 parts of polyether macromonomer 30 parts acrylic acid 25 parts of methylpropenyl tartaric acid 12 parts of sodium methyl allyl sulfonate 4 parts mercaptopropionic acid 3 parts potassium persulfate 1.5 parts sodium metabisulfite 450 parts deionized water Raw material characteristics description Polyether macromonomer (EPEG): The double bond is directly connected to the oxygen atom, which has high reactivity and a large degree of freedom in the side chain. It can reduce steric resistance, enhance steric hindrance, and improve the dispersion effect on cement particles.

[0042] Methacrylic tartaric acid (MJ): Contains dicarboxyl and methyl hydrophobic groups, which can increase carboxyl density, enhance the adsorption capacity of cement and silica fume, and at the same time regulate the hydrophilic-lipophilic balance (HLB) value to promote the release of free water.

[0043] Sodium methyl allyl sulfonate (SMAS): It provides sulfonic acid groups to enhance electrostatic repulsion and assist in viscosity reduction. The methyl groups it contains can adjust the HLB value. When introduced in appropriate amounts, it can generate microbubbles and reduce the viscosity of cement paste.

[0044] Mercaptopropionic acid (chain transfer agent): Compared with mercaptoethanol, mercapto is more stable and can more precisely control the distribution of polymer chain length, further reducing the viscosity increase caused by intermolecular entanglement of water-reducing agents.

[0045] Preparation method Step 1: Setting viscosity reduction targets Target performance parameters: apparent viscosity of cement paste ≤1000MPa•s (when fluidity is 250±10mm); initial fluidity of mortar ≥250mm, retention rate ≥85% after 30min.

[0046] Step 2: Preparation of the base solution Add EPEG to deionized water, control the temperature to 30°C, and stir until completely dissolved (solution transmittance ≥95%) to obtain the synthesis base solution.

[0047] Step 3: Preparation of premixed solution Solution A: Dissolve acrylic acid, methacryl tartaric acid, and sodium methyl allyl sulfonate in deionized water in proportion and stir until homogeneous.

[0048] Solution B: Dissolve the chain transfer agent and reducing agent in deionized water and stir until completely dissolved.

[0049] Step 4: Copolymerization Add the oxidant to the base solution and mix thoroughly by stirring at 350 rpm. Simultaneously add solution A and solution B: Solution A dropping time: 60 min, dropping rate: uniform; Solution B addition time: 70 min, added at a uniform rate; After the addition is complete, maintain the temperature at 30℃ for 60 minutes, then cool to room temperature and adjust the pH to 8 with a 30% NaOH aqueous solution to obtain a viscosity-reducing polycarboxylate superplasticizer.

[0050] Performance verification Viscosity reduction effect test: The viscosity reduction effect was verified by measuring the apparent viscosity of cement paste (target ≤1000MPa•s) and the flow time of concrete slump cone (target ≤20s). Dispersion performance test: The initial fluidity of cement mortar is ≥250mm, and the fluidity loss rate after 30 minutes is ≤15%; Strength test: 28-day compressive strength of concrete ≥125MPa (based on the standard mix).

[0051] Example 3 Raw material components and weight parts of viscosity-reducing polycarboxylate superplasticizer based on molecular structure optimization Raw material composition and weight parts: 360 parts of polyether macromonomer 25 parts acrylic acid 20 parts of methylpropenyl tartaric acid 10 parts of sodium methyl allyl sulfonate 3 parts of dodecyl mercaptan 2 parts of ammonium persulfate 1 part sodium ascorbate 420 portions of deionized water Raw material characteristics description Polyether macromonomer (EPEG): The double bond is directly connected to the oxygen atom, which has high reactivity and a large degree of freedom in the side chain. It can reduce steric resistance, enhance steric hindrance, and improve the dispersion effect on cement particles.

[0052] Methacrylic tartaric acid (MJ): Contains dicarboxyl and methyl hydrophobic groups, which can increase carboxyl density, enhance the adsorption capacity of cement and silica fume, and at the same time regulate the hydrophilic-lipophilic balance (HLB) value to promote the release of free water.

[0053] Sodium methyl allyl sulfonate (SMAS): It provides sulfonic acid groups to enhance electrostatic repulsion and assist in viscosity reduction. The methyl groups it contains can adjust the HLB value. When introduced in appropriate amounts, it can generate microbubbles and reduce the viscosity of cement paste.

[0054] Preparation method Step 1: Setting viscosity reduction targets Target performance parameters: apparent viscosity of cement paste ≤1000MPa•s (when fluidity is 250±10mm); initial fluidity of mortar ≥250mm, retention rate ≥85% after 30min.

[0055] Step 2: Preparation of the base solution Add EPEG to deionized water, control the temperature to 32°C, and stir until completely dissolved (solution transmittance ≥95%) to obtain the synthesis base solution.

[0056] Step 3: Preparation of premixed solution Solution A: Dissolve acrylic acid, methacryl tartaric acid, and sodium methyl allyl sulfonate in deionized water in proportion and stir until homogeneous.

[0057] Solution B: Dissolve the chain transfer agent and reducing agent in deionized water and stir until completely dissolved.

[0058] Step 4: Copolymerization Add the oxidant to the base solution and mix thoroughly at 300-350 rpm. Simultaneously add solution A and solution B dropwise. Solution A dropping time: 60 min, dropping rate: uniform; Solution B addition time: 70 min, added at a uniform rate; After the addition is complete, maintain the temperature at 32℃ for 60 minutes, then cool to room temperature and adjust the pH to 7-8 with a 30% NaOH aqueous solution to obtain a viscosity-reducing polycarboxylate superplasticizer.

[0059] Performance verification Viscosity reduction effect test: The viscosity reduction effect was verified by measuring the apparent viscosity of cement paste (target ≤1000MPa•s) and the flow time of concrete slump cone (target ≤20s). Dispersion performance test: The initial fluidity of cement mortar is ≥250mm, and the fluidity loss rate after 30 minutes is ≤15%; Strength test: 28-day compressive strength of concrete ≥125MPa (based on the standard mix).

[0060] As can be seen from the above embodiments, the present invention provides a polycarboxylate superplasticizer with excellent viscosity-reducing effect and comprehensive performance. This superplasticizer can significantly reduce the viscous resistance between cement paste and concrete, giving concrete good initial fluidity and excellent fluidity retention ability, meeting the workability requirements of pumped construction. Simultaneously, the product of the present invention can effectively stabilize the air content of concrete at a low level, ensuring the dense structure of hardened concrete, thereby significantly improving its compressive strength at all ages. The preparation method is simple, with mild conditions, and the resulting product has stable performance and good reproducibility, providing an efficient and reliable admixture option for the preparation of high-performance concrete.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A viscosity-reducing polycarboxylate superplasticizer, characterized in that, It is prepared by copolymerization of the following raw materials in parts by weight: 350-380 parts polyether macromonomer, 20-30 parts acrylic acid, 15-25 parts methacrylic tartaric acid, 8-12 parts sodium methyl allyl sulfonate, 2-4 parts chain transfer agent, 1.5-3 parts oxidant, 0.8-1.5 parts reducing agent, and 400-450 parts deionized water; The polyether macromonomer is an EPEG-type polyether macromonomer.

2. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The chain transfer agent is selected from one of mercaptoethanol, mercaptopropionic acid, or dodecyl mercaptan.

3. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The oxidant is selected from either ammonium persulfate or potassium persulfate.

4. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The reducing agent is selected from sodium sulfite, sodium metabisulfite, or sodium ascorbate.

5. The method for preparing the viscosity-reducing polycarboxylate superplasticizer according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Preparation of base solution: Add the polyether macromonomer to deionized water and stir at 30~35℃ until completely dissolved to obtain the synthesis base solution; S2. Preparation of premixed solution: Dissolve acrylic acid, methacryl tartaric acid and sodium methyl allyl sulfonate in deionized water to obtain solution A; dissolve chain transfer agent and reducing agent in deionized water to obtain solution B; S3. Copolymerization reaction: Add an oxidant to the synthesis base solution and stir to mix well. Then, add solution A and solution B dropwise simultaneously. After the addition is complete, keep the reaction at 30~35℃. Then, adjust the pH value to 7~8 with alkaline solution to obtain the viscosity-reducing polycarboxylate superplasticizer.

6. The preparation method according to claim 5, characterized in that, In step S1, the solution is stirred until the transmittance is ≥95%.

7. The preparation method according to claim 5, characterized in that, In step S3, after adding the oxidant, mix at a stirring speed of 300~350 rpm.

8. The preparation method according to claim 7, characterized in that, In step S3, the heat preservation reaction time is 40~100min.

9. The preparation method according to claim 5, characterized in that, In step S3, the alkaline solution is a 30% (w / w) sodium hydroxide aqueous solution.

10. The application of the viscosity-reducing polycarboxylate superplasticizer according to any one of claims 1 to 4 or the viscosity-reducing polycarboxylate superplasticizer prepared by the preparation method according to any one of claims 5 to 9 in the preparation of concrete.