High-solid-content low-bleeding type polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention relates to the technical field of preparation of water reducing agents, in particular to a high-solid-content low-bleeding type polycarboxylic acid water reducing agent and a preparation method thereof. The preparation method comprises the following steps: mixing tea polyphenol and inorganic alkali in an organic solvent under the conditions of inert atmosphere and ice-water bath, heating, dropwise adding a sulfonate monomer, and separating and purifying to obtain a tea polyphenol-based polysulfonic acid solubilizer; the preparation method comprises the following steps: mixing and dissolving a polyether macromonomer and water, adding the solubilizer and unsaturated silane ester, and carrying out copolymerization reaction with an unsaturated small monomer under the action of an initiator and a molecular weight regulator to obtain the polycarboxylate superplasticizer with solid content of 70-80%. By introducing the tea polyphenol-based polysulfonic acid solubilizer and the unsaturated silane ester, the unification of high solid content and low viscosity of the system is synergistically realized, the product is endowed with excellent low bleeding characteristic and long-term storage stability, and the technical problems of high viscosity, easy bleeding and poor slump loss resistance of the traditional high-solid-content water reducing agent are effectively solved.

Description

Technical Field

[0001] This invention relates to the technical field of water-reducing agent preparation, and particularly to a high-solids-content, low-bleeding polycarboxylate water-reducing agent and its preparation method. Background Technology

[0002] Water-reducing agents, as important concrete admixtures, can effectively reduce the unit water consumption while maintaining a relatively constant concrete slump, thereby improving the strength and durability of concrete. They have become an indispensable component in modern concrete mix design. Currently common types of high-efficiency water-reducing agents include naphthalene-based, sulfonated melamine resin-based, fatty acid-based, aminosulfonate-based, modified lignin sulfonate-based, and polycarboxylate-based agents. Among these, polycarboxylate-based high-performance water-reducing agents have developed rapidly and are widely used in various fields such as water conservancy, bridges, and marine engineering.

[0003] However, polycarboxylate superplasticizers are quite sensitive to fluctuations in raw material prices and temperature changes during practical applications. Especially when the aggregates are relatively clean or the ambient temperature is low, they can easily cause adverse phenomena such as increased delayed fluidity and bleeding in concrete, directly affecting the workability of fresh concrete and limiting their further promotion. Therefore, improving the delayed bleeding problem of this type of superplasticizer has become a pressing technical challenge that needs to be addressed.

[0004] On the other hand, most existing polycarboxylate superplasticizers on the market have a solids content between 40% and 50%, resulting in high transportation costs and poor economic viability in the face of fierce market competition, thus hindering their industrialization. Meanwhile, some high-solids-content products suffer from unstable performance and high solution viscosity, increasing the load on the conveying pumps, accelerating equipment wear, and affecting their applicability in large-scale projects.

[0005] While there are existing reports on high-solids-content polycarboxylate superplasticizers, such as invention patents with publication numbers CN107721232A and CN105778014A, their solids content is mostly limited to below 65%, failing to effectively resolve the technical contradiction of high viscosity and bleeding problems coexisting. Invention patent with publication number CN113736036A discloses a multi-arm type polycarboxylate superplasticizer and its preparation method, which involves terminal halogenation of unsaturated polyether macromonomers and then applying them to the synthesis of polycarboxylate superplasticizers. The polycarboxylate superplasticizers prepared using this type of polyether macromonomer mainly improve shrinkage performance, but lack the function of low bleeding, and the solids content of the prepared product is lower than that of this patent, which is different from the preparation method of this invention patent.

[0006] In summary, the development of high-performance polycarboxylate superplasticizers with high solids content, low viscosity, and the ability to effectively suppress bleeding is of great practical significance for promoting technological progress and engineering applications in the industry. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing a high-solids-content, low-bleeding polycarboxylate superplasticizer, comprising the following steps: S1. Under an inert atmosphere and ice-water bath, add water, organic solvent, tea polyphenols and inorganic base, stir evenly and heat, slowly add sulfonate monomer, and after the reaction is completed, separate and purify to obtain tea polyphenol-based polysulfonic acid solubilizer. S2. After the polyether macromonomer M is mixed and dissolved evenly with water, the prepared tea polyphenol-based polysulfonic acid solubilizer and unsaturated silane ester are added and mixed evenly. Then, unsaturated small monomers, initiator aqueous solution and molecular weight regulator aqueous solution are added dropwise. After the reaction is completed, the pH value of the system is adjusted to obtain the high solids content and low water bleeding type polycarboxylate superplasticizer.

[0008] Furthermore, in step S1, the mass ratio of tea polyphenols, sulfonate monomers, inorganic bases and organic solvents is 1:(1.8-5.0):(0.5-2.0):(5-10).

[0009] Furthermore, in step S1, the sulfonate monomer is one or more combinations of 1,3-propanesulfonate lactone, 1,4-butanesulfonate lactone and 2,4-butanesulfonate. In step S1, the inorganic base is potassium hydroxide or sodium hydroxide, and the organic solvent is tetrahydrofuran.

[0010] Furthermore, in step S2, the mass ratio of the polyether macromonomer M, tea polyphenol-based polysulfonic acid solubilizer, unsaturated silane ester, and unsaturated small monomer is 200:(2-12):(2-8):(12-42).

[0011] Further, in step S2, the unsaturated silane ester is one or a combination of (phenyl dimethylsilyl)methacrylate, methyl(2E)-3-{2-[(trimethylsilyl)oxy]phenyl}acrylate, methyl(2E)-3-{3,4-di[(trimethylsilyl)oxy]phenyl}acrylate, methyl(2E)-3-{3-[(trimethylsilyl)oxy]phenyl}acrylate, trimethylsilyl(2E)-3-(4-methoxyphenyl)acrylate, and trimethylsilyl(2E)-3-(3,4-dimethoxyphenyl)acrylate.

[0012] Furthermore, in step S2, the polyether macromonomer M is one or more combinations of 3-methyl-3-butene-1-polyethylene glycol, 2-methylallyl polyethylene glycol, ethylene glycol monovinyl polyethylene glycol ether, and 4-hydroxybutylvinyl polyoxyethylene ether, with a molecular weight of 600-6000.

[0013] Furthermore, in step S2, the initiator is a water-soluble inorganic peroxide initiator or a water-soluble redox initiation system; The water-soluble inorganic peroxide initiator is at least one of ammonium persulfate and potassium persulfate; the water-soluble redox initiation system includes an oxidant and a reductant, wherein the oxidant is selected from hydrogen peroxide or persulfate, and the reductant is selected from one or more combinations of sodium formaldehyde sulfoxylate, ascorbic acid, glucose, or sodium bisulfite.

[0014] Furthermore, in step S2, the molecular weight regulator is one or more combinations of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, isopropanol, sodium hypophosphite, trisodium phosphate, sodium formate, sodium acetate, and dodecyl mercaptan. The unsaturated monomer is an unsaturated carboxylic acid and / or an unsaturated carboxylic anhydride, wherein the unsaturated carboxylic acid and / or unsaturated carboxylic anhydride is one or more combinations of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, acrylic anhydride and itaconic anhydride.

[0015] Preferably, in step S2, the total amount of water used is such that after the reaction is completed, the mass concentration of solid polymer (copolymer product) in the final product, high solid content polycarboxylate superplasticizer, is 70% to 80%.

[0016] The amount of the initiator is 0.5 to 5.0% of the total mass of the solute in the comonomer mixture solution, and the amount of the molecular weight regulator is 0.2 to 3.0% of the total mass of the solute in the comonomer mixture solution.

[0017] It should be noted that the comonomer mixture solution is a mixed aqueous solution formed in step S2 by dissolving polyether macromonomer M, tea polyphenol-based polysulfonic acid solubilizer, and unsaturated small monomers in water. The total mass of all dissolved comonomers in this solution is used as a basis for calculating the amount of initiator and molecular weight regulator.

[0018] Furthermore, in step S1, the temperature of the ice-water bath is 0-5℃; after stirring evenly, the temperature is raised to 30-50℃; the time for slowly adding the sulfonate monomer is 0.5-2h; after the addition is completed, the reaction continues for 12-20h, and then the temperature is lowered before separation and purification. In step S2, when the polyether macromonomer M is mixed and dissolved with water, the temperature is raised to 20-45°C, and then the temperature is adjusted to the reaction initiation temperature, which is 5-60°C. The addition time of the unsaturated monomer, initiator aqueous solution, and molecular weight regulator aqueous solution is 0.5-2.0 h; the reaction temperature is controlled at 5-60℃; after the addition is completed, the reaction continues for 0.5-1.0 h; the pH value of the system is adjusted to 5-7 with alkali.

[0019] The present invention also provides a high-solids-content, low-bleeding polycarboxylate superplasticizer, which is prepared by the method described above.

[0020] Compared with the prior art, the high-solids-content, low-bleeding polycarboxylate superplasticizer and its preparation method provided by the present invention have the following beneficial effects: 1. The key breakthrough of this invention lies in its unique molecular construction pathway: under alkaline catalytic conditions, the phenolic hydroxyl groups of tea polyphenols undergo a nucleophilic ring-opening reaction with cyclic sulfonates, thereby achieving efficient grafting of sulfonate groups onto multiple phenolic sites of the rigid framework of tea polyphenols in one step, forming structurally regular polysulfonic acid derivatives. When used to prepare polycarboxylate superplasticizers, the densely packed sulfonate groups on the periphery form a stable, high-density charge barrier. This barrier, through strong electrostatic repulsion and steric hindrance, dually inhibits the disordered entanglement between polycarboxylate molecular chains, exhibiting a significant "solubilizing" effect. Macroscopically, this synergistic effect of the microscopic mechanism allows the system to significantly increase solids content while simultaneously reducing viscosity, successfully breaking away from the traditional approach of relying on carboxyl groups for performance regulation in polycarboxylate superplasticizers, and opening up a new direction for the molecular architecture design of next-generation high-performance superplasticizers. 2. This invention achieves a dynamic and intelligent dispersion retention effect by introducing a silane ester functional structure and compounding it with tea polyphenol polysulfonic acid derivatives. The flexible molecular chain of the water-reducing agent ensures rapid adsorption and dispersion in the early stage; while the synergistic effect of the two enhances the universality for complex materials and eliminates delayed bleeding. In the later stage, the directional hydrolysis behavior of the ester group begins to dominate, continuously generating new carboxyl adsorption sites, cleverly compensating for the dispersion components consumed by hydration, thereby achieving long-term maintenance of slurry fluidity. 3. This invention patent benefits from the complete introduction of the core structure of tea polyphenols at the molecular level, allowing the prepared product to naturally inherit the antioxidant and antimicrobial activity capabilities inherent in its source. This endows the final water-reducing agent product with an endogenous preservative function, effectively resisting system rancidity and performance degradation caused by microbial growth during warehousing and storage. This characteristic achieves an organic unity between high water-reducing performance and long-term storage stability, fundamentally changing the passive situation of traditional formulations that must rely on external chemical preservatives to maintain shelf life; 4. In terms of application performance, products manufactured using this patent can achieve a high solids content of 70% to 80% while maintaining a low system viscosity, which effectively reduces the load on the conveying pump when transporting materials. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 (1) Place the reactor in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 102g water, 530g tetrahydrofuran, 100g tea polyphenols and 60g sodium hydroxide, stir evenly, stir and heat to 30℃, slowly add 216g 1,3-propanesulfonic acid lactone, add it over 0.5h, continue stirring and react for 13h, cool down, stop the reaction, and then separate and purify to obtain tea polyphenol-based polysulfonic acid solubilizer KZJ-ZR1.

[0023] (2) Add 130g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000, 70g of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, and 88g of water to a reaction vessel, heat to 35-45℃, and stir until the polyether macromonomer is uniformly dissolved. Then adjust the temperature to the reaction initiation temperature, add 8g of the above-prepared KZJ-ZR1, 2g of (phenyldimethylsilyl) methyl methacrylate, 5g of maleic anhydride, 0.018g of ferrous sulfate, and 2.2g of water. After the materials are mixed evenly, add 23g of unsaturated monomer (acrylic acid), 1.0g of ascorbic acid aqueous solution (1.0g of ascorbic acid and 5g of water), and 1.7g of mercaptoacetic acid aqueous solution (1.7g of mercaptoacetic acid and 5g of water) dropwise over 1.0h. The initial reaction temperature is 5-15℃, and the material temperature is controlled to ≤35℃ during the dropwise addition process. After the dropwise addition is completed, continue the reaction for 1.0h, and then adjust the pH to 5-7 with alkali to obtain KZJ1, a high solids content, low water bleeding type polycarboxylate superplasticizer with a solids content of 71%.

[0024] Example 2 (1) Place the reaction vessel in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 122g water, 808 tetrahydrofuran, 100g tea polyphenols and 117 sodium hydroxide, stir evenly, stir and heat to 40℃, slowly add 152g 1,4-butyric acid lactone and 172g 1,3-propanesulfonic acid lactone, add dropwise over 1.0h, continue stirring and react for 14h, cool down, stop the reaction, and then separate and purify to obtain tea polyphenol-based polysulfonic acid solubilizer KZJ-ZR2.

[0025] (2) Add 180g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000, 20g of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, 0.015g of ferrous sulfate and 90g of water to a reaction vessel, heat to 35-45℃, and stir until the polyether macromonomer is uniformly dissolved. Then adjust the temperature to the reaction initiation temperature, add 10g of the above-prepared KZJ-ZR2, 3g of methyl(2E)-3-{2-[(trimethylsilyl)oxy]phenyl}acrylate, and 2.2g of water. After the materials are mixed evenly, add 28g of unsaturated monomers (acrylic acid, 4g of methacrylic acid), an aqueous solution of sodium formaldehyde sulfoxylate (0.8g of sodium formaldehyde sulfoxylate and 5g of water), and an aqueous solution of mercaptoethanol (1.8g of mercaptoethanol and 5g of water) dropwise over 1.0h. The initial reaction temperature is 10-15℃, and the material temperature is controlled to ≤45℃ during the dropwise addition process. After the dropwise addition is completed, continue the reaction for 1.0h, and then adjust the pH to 5-7 with alkali to obtain KZJ2, a high-solids, low-bleeding polycarboxylate superplasticizer with a solids content of 71%.

[0026] Example 3 (1) Place the reactor in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 165g water, 906 tetrahydrofuran, 100g tea polyphenols and 166g sodium hydroxide, stir evenly, stir and heat to 50℃, slowly add 202g 2,4-butyrosine lactone and 246g 1,3-propanesulfonic acid lactone, add dropwise over 1.5h, continue stirring and react for 15h, cool down, stop the reaction, and then separate and purify to obtain tea polyphenol-based polysulfonic acid solubilizer KZJ-ZR3.

[0027] (2) Add 200g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000 and 90g of water to the reactor, heat to 35-45℃, and stir until the polyether macromonomer is evenly dissolved. Then adjust the temperature to the reaction start temperature, add 12g of the KZJ-ZR3 prepared above, 5g of methyl(2E)-3-{3,4-di[(trimethylsilyl)oxy]phenyl}acrylate, 0.022g of ferrous sulfate and 1.8g of hydrogen peroxide, and wait for the materials to settle. After thorough mixing, unsaturated monomers (36g acrylic acid), ascorbic acid aqueous solution (1.0g glucose and 5g water), and mercaptoethanol aqueous solution (2.0g mercaptoethanol and 5g water) are added dropwise over 1.0h. The initial reaction temperature is 15-20℃, and the material temperature is controlled to ≤50℃ during the dropwise addition process. After the dropwise addition is complete, the reaction continues for 1.0h, and then the pH is adjusted to 5-7 with alkali to obtain KZJ3, a high-solids, low-bleeding polycarboxylate superplasticizer with a solids content of 72%.

[0028] Example 4 (1) Place the reactor in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 106g water, 710 tetrahydrofuran, 100g tea polyphenols and 85g potassium hydroxide, stir evenly, stir and heat to 35℃, slowly add 202g 1,3-propanesulfonic acid lactone, add it over 0.5h, continue stirring and react for 16h, cool down, stop the reaction, and then separate and purify to obtain tea polyphenol-based polysulfonic acid solubilizer KZJ-ZR4.

[0029] (2) Add 120g of 3-methyl-3-butene-1-polyethylene glycol with a molecular weight of 2400, 80g of 2-methylallyl polyethylene glycol with a molecular weight of 2400 and 60g of water to a reaction vessel, heat to 20-40℃, and stir until the polyether macromonomer is dissolved evenly. Add 10g of the KZJ-ZR4 prepared above, 6g of methyl(2E)-3-{3-[(trimethylsilyl)oxy]phenyl}acrylate and 6g of hypophosphite. Sodium was added dropwise after the materials were mixed evenly, along with unsaturated monomers (36g acrylic acid, 4g methacrylic acid) and an aqueous solution of ammonium persulfate (2.2g ammonium persulfate and 10g water). The dropwise addition took 2.0 hours, with an initial reaction temperature of 20–40°C. The material temperature was controlled to be ≤60°C during the dropwise addition. After the dropwise addition was complete, the reaction continued for 1.0 hour. The pH was then adjusted to 5–7 with alkali to obtain KZJ4, a high-solids, low-bleeding polycarboxylate superplasticizer with a solids content of 79%.

[0030] Example 5 (1) Preparation of solubilizer: The reaction vessel was placed in an ice-water bath at 0-5℃, and nitrogen gas was introduced to remove oxygen. 103g water, 755g tetrahydrofuran, 100g tea polyphenols and 108g potassium hydroxide were added and stirred evenly. The mixture was stirred and heated to 40℃. 150g 1,3-propanesulfonic acid lactone and 172g 1,4-butanesulfonic acid lactone were slowly added dropwise over 1.0h. The mixture was stirred and reacted for 20h. The temperature was lowered and the reaction was stopped. The mixture was then separated and purified to obtain tea polyphenol-based polysulfonic acid solubilizer KZJ-ZR5.

[0031] (2) Add 150g of 3-methyl-3-butene-1-polyethylene glycol with a molecular weight of 2400, 50g of 2-methylallyl polyethylene glycol with a molecular weight of 2400 and 60g of water to the reaction vessel, heat to 20-40℃, stir until the polyether macromonomer is dissolved evenly, add 9g of the KZJ-ZR5 prepared above, 7g of trimethylsilyl (2E)-3-(4-methoxyphenyl)acrylate, 3g of sodium hypophosphite and 2g of trisodium phosphate, after the materials are mixed evenly, add dropwise unsaturated small monomer (24g acrylic acid) and ammonium persulfate aqueous solution (2.6g ammonium persulfate and 10g water), the dropwise addition time is 2.0h, the initial reaction temperature is 20-40℃, and the material temperature is controlled ≤60℃ during the dropwise addition process; after the dropwise addition is completed, continue the reaction for 1.0h, and then adjust the pH to 5-7 with alkali to obtain the high solids content and low water bleeding type polycarboxylate superplasticizer KZJ-5 with a solids content of 78%.

[0032] Example 6 (1) Preparation of solubilizer: The reaction vessel was placed in an ice-water bath at 0-5℃, and nitrogen gas was introduced to remove oxygen. 106g of water, 672g of tetrahydrofuran, 100g of tea polyphenols and 80g of potassium hydroxide were added and stirred evenly. The mixture was stirred and heated to 45℃. 288g of 1,3-propanesulfonic acid lactone was slowly added dropwise over 0.5h. The reaction was continued to be stirred for 12h. The temperature was lowered and the reaction was stopped. The mixture was then separated and purified to obtain tea polyphenol-based polysulfonic acid solubilizer KZJ-ZR6.

[0033] (2) Add 90g of 3-methyl-3-butene-1-polyethylene glycol with a molecular weight of 2400, 110g of 2-methylallyl polyethylene glycol with a molecular weight of 2400 and 60g of water to a reaction vessel, heat to 20-40℃, and stir until the polyether macromonomer is uniformly dissolved. Add 7g of the above-prepared KZJ-ZR5, 8g of trimethylsilyl (2E)-3-(3,4-dimethoxyphenyl)acrylate, 3g of itaconic anhydride, 1.8g of sodium hypophosphite and 2g of sodium bisulfite, and wait... After the materials are mixed evenly, unsaturated monomers (30g acrylic acid, 3g methacrylic acid), sodium persulfate aqueous solution (3g ammonium persulfate and 8g water), and mercaptoethanol aqueous solution (0.4g mercaptoethanol and 2g water) are added dropwise over a period of 2.0 hours. The initial reaction temperature is 20-40℃, and the material temperature is controlled to be ≤60℃ during the dropwise addition process. After the dropwise addition is completed, the reaction continues for another 1.0 hour. Then, the pH is adjusted to 5-7 with alkali to obtain KZJ6, a high-solids, low-bleeding polycarboxylate superplasticizer with a solids content of 78%.

[0034] Comparative Example 1 The commercially available product has a solid content of 60% and is designated as ALT polycarboxylate superplasticizer Y1.

[0035] Comparative Example 2 Y2 was prepared by using the process in Example 1 as the basic process, without using KZJ-ZR1 synthesis, while keeping other reaction conditions unchanged.

[0036] Comparative Example 3 Based on the process in Example 1, Y3 was synthesized by replacing KZJ-ZR1 with an equal amount of tea polyphenols, while keeping other reaction conditions unchanged.

[0037] Comparative Example 4 Based on the process in Example 1, Y4 was synthesized by replacing KZJ-ZR1 with alkyl sulfonate (sodium dodecyl sulfonate) while keeping other reaction conditions unchanged.

[0038] Comparative Example 5 Based on the process in Example 1, Y5 was synthesized by replacing KZJ-ZR1 with glycerol instead of the product prepared by the reaction of tea polyphenols and 1,3-propanesulfonic acid lactone, while keeping other reaction conditions unchanged.

[0039] Comparative Example 6 Y6 was prepared by using the process of Example 1 as the base process, without synthesizing unsaturated silane esters, while keeping other reaction conditions unchanged.

[0040] Performance testing: 1. Solid content and viscosity test The solids content and viscosity of the high-solids-content, anti-mud polycarboxylate superplasticizers prepared in Examples 1 to 6 and the samples of Comparative Examples 1 to 6 were measured. The solids content was tested according to GB / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures". The viscosity was tested using an NDJ-8T rotational viscometer under constant temperature conditions of 5℃, 25℃, and 40℃. The test results are shown in Table 1.

[0041] Table 1 Viscosity test results

[0042] As can be seen from Table 1: As the temperature increased, the viscosity of all samples decreased.

[0043] The solid content of the sample of this invention is 70%-80%, and the viscosity is low. At 5°C, the viscosity is lower than that of a commercially available product with 60% solid content at a low temperature of 40°C. The patented product still has good fluidity at low temperatures and can be pumped.

[0044] Commercially available high-solids water-reducing agent Y1 and its comparative formulation have high viscosity, making them difficult to pump and leading to wear and tear on the pumps used in production.

[0045] 2. Concrete performance testing Runfeng P.O42.5 ordinary Portland cement was used. The concrete mix proportion was: cement 280kg / m3, fly ash 40kg / m3, mineral powder 40kg / m3, manufactured sand 835g / m3, aggregate 980kg / m3, and water 175kg / m3. Initial performance tests were conducted on the polycarboxylate superplasticizers prepared in Examples 1-6 and Comparative Examples 1-6 according to the above admixture formulation. The admixture dosage was adjusted to achieve an initial concrete spread of (520±20)mm. The concrete was then subjected to different ambient temperatures (5±3℃, 40±3℃) for performance testing. The test indicators included the concrete spread and bleeding rate after 0h, 1h, 2h, and 3h. The test results are shown in Tables 2 and 3.

[0046] Table 2. Concrete performance test results (5±3℃)

[0047] Table 3. Concrete performance test results (40±3℃)

[0048] As shown in Table 2, under low-temperature conditions (5±3℃), the samples prepared by this invention at a dosage of 0.3% exhibited good workability retention, maintaining good concrete fluidity within 3 hours without any hysteresis or bleeding, demonstrating good workability. In contrast, the comparative samples had higher dosages, and some showed hysteresis after 1 hour, significant losses after 2 hours, and a sharp decrease in spread between 2-3 hours, sometimes even becoming unmeasurable. They also exhibited higher bleeding rates and generally poor workability.

[0049] As shown in Table 3, the samples prepared under this invention patent also exhibited stability under high-temperature conditions (40±3℃). The loss in scalability over time was slightly higher than at low temperatures but remained controllable, and the bleeding rate was essentially zero, indicating good workability of the concrete. In contrast, the comparative samples showed more severe scalability loss at high temperatures. Most samples experienced a significant decrease in scalability after 2 hours, and essentially lost all fluidity after 3 hours. Although the bleeding rate was slightly lower than under low-temperature conditions, it was still significantly higher than that of the samples prepared under this invention patent.

[0050] In summary, the samples prepared by this invention can effectively maintain the fluidity and stability of concrete in both low-temperature and high-temperature environments, exhibiting excellent slump retention and low bleeding characteristics.

[0051] 3. Storage stability The high-solids-content, anti-mud polycarboxylate superplasticizers prepared in Examples 1 to 6 and the samples of Comparative Examples 1 to 6 were placed in environments of -10 to -5°C and 40 to 50°C, respectively, and the storage stability of the products at high and low temperatures was observed. The results are shown in Table 4.

[0052] Table 4 Storage stability test results

[0053] As shown in Table 3, compared with the comparative products (Comparative Examples 1 to 5), the patented products (Examples 1 to 6) showed excellent storage stability after being stored for 15 to 60 days at low temperatures of -10 to -5°C and high temperatures of 40 to 50°C, without any adverse phenomena such as solidification, clumping, stratification, off-odors, or mold growth. In contrast, the comparative samples (Y1 to Y5) generally showed solidification, clumping, or stratification at low temperatures, and after long-term storage at high temperatures, they often showed deterioration problems such as off-odors and mold growth. This fully demonstrates that the patented products have better weather resistance and long-term storage stability, and can effectively inhibit the growth of microorganisms during storage in high-temperature environments.

[0054] In summary, the high-solids, low-bleeding polycarboxylate superplasticizer prepared by this invention achieves a high solids content of 70%-80% while maintaining a significantly lower viscosity than commercially available and comparative products. Especially at 5°C, its viscosity remains lower than that of a 60% solids content commercially available product at 40°C, ensuring excellent low-temperature fluidity and pumpability. In concrete applications, this product, at a low dosage of 0.3%, effectively maintains concrete fluidity in both high and low temperature environments, exhibiting minimal spread loss within 3 hours and extremely low bleeding rate, overcoming the problems of delayed bleeding and poor slump retention inherent in traditional high-solids content products. Furthermore, the product shows no solidification, clumping, delamination, or mold growth after 60 days of storage under harsh conditions of -10 to -5°C and 40 to 50°C, demonstrating excellent chemical stability and inherent corrosion resistance. In conclusion, this product successfully achieves a balance between high solids content, low viscosity, low bleeding, and high stability, providing a reliable technical solution for high-performance concrete engineering.

[0055] Although this document frequently uses terms such as unsaturated macromonomer, solubilizer, unsaturated carboxylic acid and / or unsaturated carboxylic anhydride, initiator, and molecular weight regulator, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this invention; interpreting them as any additional limitation would be contrary to the spirit of this invention.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 invention.

Claims

1. A method for preparing a high-solids-content, low-bleeding polycarboxylate superplasticizer, characterized in that, Includes the following steps: S1. Under an inert atmosphere and ice-water bath, add water, organic solvent, tea polyphenols and inorganic base, stir evenly and heat, slowly add sulfonate monomer, and after the reaction is completed, separate and purify to obtain tea polyphenol-based polysulfonic acid solubilizer. S2. After the polyether macromonomer M is mixed and dissolved evenly with water, the prepared tea polyphenol-based polysulfonic acid solubilizer and unsaturated silane ester are added and mixed evenly. Then, unsaturated small monomers, initiator aqueous solution and molecular weight regulator aqueous solution are added dropwise. After the reaction is completed, the pH value of the system is adjusted to obtain the high solids content and low water bleeding type polycarboxylate superplasticizer.

2. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of tea polyphenols, sulfonate monomers, inorganic bases and organic solvents is 1:(1.8-5.0):(0.5-2.0):(5-10).

3. The preparation method according to claim 1, characterized in that: In step S1, the sulfonate monomer is one or more combinations of 1,3-propanesulfonate lactone, 1,4-butanesulfonate lactone and 2,4-butanesulfonate. In step S1, the inorganic base is potassium hydroxide or sodium hydroxide, and the organic solvent is tetrahydrofuran.

4. The preparation method according to claim 1, characterized in that: In step S2, the mass ratio of the polyether macromonomer M, tea polyphenol-based polysulfonic acid solubilizer, unsaturated silane ester, and unsaturated small monomer is 200:(2-12):(2-8):(12-42).

5. The preparation method according to claim 1, characterized in that: In step S2, the unsaturated silane ester is one or a combination of (phenyl dimethylsilyl)methacrylate, methyl(2E)-3-{2-[(trimethylsilyl)oxy]phenyl}acrylate, methyl(2E)-3-{3,4-di[(trimethylsilyl)oxy]phenyl}acrylate, methyl(2E)-3-{3-[(trimethylsilyl)oxy]phenyl}acrylate, trimethylsilyl(2E)-3-(4-methoxyphenyl)acrylate, and trimethylsilyl(2E)-3-(3,4-dimethoxyphenyl)acrylate.

6. The preparation method according to claim 1, characterized in that: In step S2, the polyether macromonomer M is one or more combinations of 3-methyl-3-butene-1-polyethylene glycol, 2-methylallyl polyethylene glycol, ethylene glycol monovinyl polyethylene glycol ether, and 4-hydroxybutylvinyl polyoxyethylene ether, with a molecular weight of 600-6000.

7. The preparation method according to claim 1, characterized in that: In step S2, the initiator is a water-soluble inorganic peroxide initiator or a water-soluble redox initiation system; The water-soluble inorganic peroxide initiator is at least one of ammonium persulfate and potassium persulfate; the water-soluble redox initiation system includes an oxidant and a reductant, wherein the oxidant is selected from hydrogen peroxide or persulfate, and the reductant is selected from one or more combinations of sodium formaldehyde sulfoxylate, ascorbic acid, glucose, or sodium bisulfite.

8. The preparation method according to claim 1, characterized in that: In step S2, the molecular weight regulator is one or more combinations of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, isopropanol, sodium hypophosphite, trisodium phosphate, sodium formate, sodium acetate, and dodecyl mercaptan. The unsaturated monomer is an unsaturated carboxylic acid and / or an unsaturated carboxylic anhydride, wherein the unsaturated carboxylic acid and / or unsaturated carboxylic anhydride is one or more combinations of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, acrylic anhydride and itaconic anhydride.

9. The preparation method according to claim 1, characterized in that: In step S1, the temperature of the ice-water bath is 0-5℃; after stirring evenly, the temperature is raised to 30-50℃; the sulfonate monomer is slowly added dropwise over a period of 0.5-2 hours; after the addition is complete, the reaction continues for 12-20 hours, and then the temperature is lowered before separation and purification. In step S2, when the polyether macromonomer M is mixed and dissolved with water, the temperature is raised to 20-45°C, and then the temperature is adjusted to the reaction initiation temperature, which is 5-60°C. The addition time of the unsaturated monomer, initiator aqueous solution, and molecular weight regulator aqueous solution is 0.5-2.0 h; the reaction temperature is controlled at 5-60℃; after the addition is completed, the reaction continues for 0.5-1.0 h; the pH value of the system is adjusted to 5-7 with alkali.

10. A high-solids-content, low-bleeding polycarboxylate superplasticizer, characterized in that: It is prepared by the preparation method described in any one of claims 1-10.

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