High-solid-content polycarboxylic acid slump retaining agent and preparation method thereof

Abstract

The invention relates to the technical field of preparation of slump retaining agents, in particular to a high-solid-content polycarboxylic acid slump retaining agent and a preparation method thereof. The preparation method comprises the following steps: under the conditions of inert atmosphere and ice-water bath, performing nucleophilic ring-opening reaction on tea polyphenol and sulfonate monomers in inorganic alkali and an organic solvent to prepare a tea polyphenol-based polysulfonic acid solubilizer; the preparation method comprises the following steps: mixing a polyether macromonomer, a water-locking slurry-stabilizing small monomer and water, adding the solubilizer, dropwise adding an unsaturated small monomer, unsaturated carboxylic ester, an initiator and a molecular weight regulator, carrying out a copolymerization reaction, and finally adjusting the pH value to obtain the product. According to the method, the polycarboxylic acid slump retaining agent with the solid content as high as 70%-80% and low viscosity is successfully prepared by introducing the solubilizer with a specific structure and the water-locking and slurry-stabilizing small monomer to achieve a synergistic effect. The product can effectively improve the workability of concrete, prevent delayed bleeding and significantly reduce the transportation and pumping cost, and has good storage stability.

Description

Technical Field

[0001] This invention relates to the technical field of slump retainer preparation, and particularly to a high-solids-content polycarboxylic acid slump retainer and its preparation method. Background Technology

[0002] With the ever-increasing demands on concrete performance in modern engineering construction, simply relying on high water reduction rates is no longer sufficient to meet the needs of complex engineering scenarios. Taking slump retention as an example, the large-scale application of ready-mixed concrete presents challenges such as long-distance transportation and long-term pumping from production to construction. Especially in large-volume concrete structures, ultra-long continuous pouring, and super high-rise buildings, concrete needs to maintain its fluidity for several hours or more. If the slump loss is too rapid, it will lead to pumping failure on site, pipe blockage, or even forced abandonment, resulting not only in resource waste and construction delays but also potentially quality disputes and legal risks. Therefore, the development of polycarboxylate superplasticizers with excellent slump retention performance has become an urgent need in the industry.

[0003] Currently, slump retainers are admixtures that prevent rapid loss of concrete slump. They achieve this by slowing down cement hydration and setting through the action of special functional groups. However, in existing technologies, due to significant variations in material quality, problems such as poor workability and delayed bleeding often arise in practical applications due to fluctuations in concrete material composition. Furthermore, existing products still face a key bottleneck—the solids content is generally in the 40%–50% range, severely restricting their economic viability and industrial application. While high solids content can improve efficiency, it leads to excessively high solution viscosity, increasing the load on the conveying pump and potentially causing equipment wear, thus limiting the product's efficient application in large-scale projects. For example, CN107721232A discloses a high-solids-content slow-release polycarboxylate superplasticizer with a solids content of 55%–65%; CN105778014B also reports a high-solids-content polycarboxylate superplasticizer with a solids content of 50%–63.4%. However, the solid content of these existing technology products is still at a moderate level, and they have not effectively solved the problem that high solid content inevitably leads to high viscosity. Their water-locking and stabilizing properties in concrete also have room for improvement. Another method, such as the one described in CN1167739A, has a complex preparation process and suffers from excessive slump loss over time.

[0004] Therefore, developing a polycarboxylate slump retainer that combines high solids content with low viscosity has become a key technical problem that the industry urgently needs to overcome. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a method for preparing a high-solids-content polycarboxylic acid slump retainer, 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 and the water-locking and slurry-stabilizing monomer are mixed and dissolved evenly with water, the prepared tea polyphenol-based polysulfonic acid solubilizer is added, and after mixing evenly, the unsaturated monomer, unsaturated carboxylic acid ester, 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 polycarboxylic acid slump retainer.

[0006] 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).

[0007] 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 lactone; the inorganic base is potassium hydroxide or sodium hydroxide; and the organic solvent is tetrahydrofuran.

[0008] Furthermore, in step S2, the mass ratio of the polyether macromonomer M, tea polyphenol-based polysulfonic acid solubilizer, unsaturated small monomer, water-locking and slurry-stabilizing small monomer, and unsaturated carboxylic acid ester is 200: (2-10): (2-15): (2-8): (10-35).

[0009] Furthermore, the water-locking and stabilizing monomer is one or more combinations of bis(3-trimethoxysilylpropyl) fumarate, bis(3-trimethoxysilylpropyl) maleate, and bis(3-trimethoxysilylethyl) fumarate.

[0010] Furthermore, the unsaturated carboxylic acid ester is one or more combinations of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol 1,3-diacrylate, pentylene glycol 1,5-dimethacrylate, and glycerol 1,3-diisobutylene ester.

[0011] Furthermore, the polyether macromonomer M is one or more of the following: 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. 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.

[0012] Furthermore, 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. 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.

[0013] 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 polycarboxylic acid water-reducing agent, is 70% to 80%.

[0014] 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.

[0015] 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.

[0016] 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 and the water-locking and slurry-stabilizing monomer are 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, unsaturated carboxylic acid ester, 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.

[0017] The present invention also provides a high-solids-content polycarboxylic acid slump retainer, which is prepared by the method described above.

[0018] Compared with the prior art, the high-solids-content polycarboxylic acid slump retainer and its preparation method provided by the present invention have the following beneficial effects: 1. This invention utilizes the nucleophilic ring-opening reaction between the phenolic hydroxyl groups in tea polyphenol molecules and cyclic sulfonates in an alkaline environment to successfully achieve selective sulfonation, thereby constructing a multi-component sulfonated structure with tea polyphenols as the rigid center and multiple phenolic hydroxyl sites replaced by sulfonate groups. When this structure is introduced as a functional monomer into a polycarboxylic acid slump retainer system, the high-density sulfonate groups formed on its molecular periphery can construct a strong charge repulsion layer. Combined with steric hindrance, this significantly prevents the entanglement between polycarboxylic acid molecular chains, resulting in molecular-level solubilization. This synergistic effect manifests macroscopically as a decrease in the viscosity of the material system while a significant increase in solids content, overcoming the bottleneck of traditional polycarboxylic acid water-reducing agents that rely solely on carboxyl groups for performance regulation.

[0019] 2. This invention innovatively introduces a water-locking and slurry-stabilizing small monomer, grafted onto the polycarboxylic acid molecular backbone. This monomer synergistically interacts with the ester groups in the molecular chain to effectively regulate the slow-release behavior of the slump-retaining components, making the release process more stable and longer-lasting. This significantly improves the workability retention of concrete, not only delaying slump loss but also effectively inhibiting delayed bleeding, while simultaneously enhancing the cohesiveness and overall water retention of the slurry, achieving precise control of the rheological properties of concrete.

[0020] 3. The product prepared by this invention retains the natural antioxidant and antibacterial activity of the tea polyphenol core integrated at the molecular level. The final product has endogenous preservative function, which can effectively inhibit the growth of microorganisms and system deterioration during storage, and achieves the unity of long-term slump retention performance and long-term stability, breaking through the limitation of traditional formulas that require the addition of chemical preservatives.

[0021] 4. The product prepared by the method of the present invention has a solid content of up to 70%-80% and a low viscosity, which reduces the load on the feed pump. Compared with the traditional 40% solid content polycarboxylate slump retainer, the production efficiency is significantly improved. Detailed Implementation

[0022] 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.

[0023] Example 1 (1) Place the reactor in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 100g water, 512g tetrahydrofuran, 100g tea polyphenols and 60g sodium hydroxide, stir evenly, stir and heat to 30℃, slowly add 215g 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.

[0024] (2) Add 120g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000, 80g of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, 4g of bis(3-trimethoxysilylpropyl) fumarate and 80g of water to a reaction vessel, heat to 35-45℃, and stir until the polyether macromonomer is dissolved evenly. Then adjust the temperature to the reaction initiation temperature, add 4g of the KZJ-ZR1 prepared above, 0.018g of ferrous sulfate and 2.4g of hydrogen peroxide, and after the materials are mixed evenly, drop... Unsaturated monomers and unsaturated carboxylic acid esters (4g acrylic acid, 20g hydroxyethyl acrylate and 8g ethylene glycol diacrylate), ascorbic acid aqueous solution (0.8g ascorbic acid and 5g water) and mercaptoacetic acid aqueous solution (2.2g mercaptoacetic acid and 5g water) are added 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, the reaction continues for 1.0h, and then the pH is adjusted to 5-7 with alkali to obtain high-solids polycarboxylic acid slump retainer PCE1 with a solids content of 73%.

[0025] Example 2 (1) Place the reactor in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 130g water, 808g tetrahydrofuran, 100g tea polyphenols and 120g sodium hydroxide, stir evenly, stir and heat to 40℃, slowly add 152g 1,4-butyric acid lactone and 178g 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.

[0026] (2) Add 160g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000, 40g of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, 0.015g of ferrous sulfate, 6g of bis(3-trimethoxysilylpropyl) fumarate and 90g of water to a reaction vessel, heat to 35-45℃, and stir until the polyether macromonomer is dissolved evenly. Then adjust the temperature to the reaction start temperature, add 5g of the KZJ-ZR2 prepared above and 2g of hydrogen peroxide. After the materials are mixed evenly, add unsaturated small monomers and unsaturated carboxyl groups dropwise. The following solutions were prepared: esters (3g acrylic acid, 3g methacrylic acid, 22g hydroxyethyl acrylate, 5g hydroxypropyl acrylate, 3g propylene glycol 1,3-dipropionate), an aqueous solution of sodium formaldehyde sulfoxylate (0.8g sodium formaldehyde sulfoxylate and 5g water), and an aqueous solution of mercaptoethanol (2.8g mercaptoethanol and 5g water). The addition time was 1.0 h, the initial reaction temperature was 10–15℃, and the material temperature was controlled to ≤45℃ during the addition process. After the addition was completed, the reaction continued for 1.0 h, and then the pH was adjusted to 5–7 with alkali to obtain high-solids polycarboxylic acid slump retainer PCE2 with a solids content of 71.6%.

[0027] Example 3 (1) Place the reactor in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 150g water, 880g tetrahydrofuran, 100g tea polyphenols and 166g sodium hydroxide, stir evenly, stir and heat to 50℃, slowly add 202g 2,4-butyrosine lactone and 248g 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.

[0028] (2) Add 200g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000 and 90g of water to the reaction vessel, heat to 35-45℃, and stir until the polyether macromonomer is dissolved evenly. Then adjust the temperature to the reaction start temperature, add 7g of the KZJ-ZR3 prepared above, 0.020g of ferrous sulfate, 8g of bis(3-trimethoxysilylpropyl)maleate and 2.6g of hydrogen peroxide. After the materials are mixed evenly, add dropwise unsaturated small monomers and unsaturated carboxylic acid esters (8g of acrylic acid). The following solutions were prepared: 24g hydroxyethyl acrylate, 6g hydroxypropyl acrylate, and 5g glycidyl methacrylate; ascorbic acid aqueous solution (1.0g glucose and 5g water); and mercaptoethanol aqueous solution (1.2g mercaptoacetic acid and 5g water). The addition time was 1.0h, the initial reaction temperature was 15-20℃, and the material temperature was controlled ≤50℃ during the addition process. After the addition was completed, the reaction continued for 1.0h, and then the pH was adjusted to 5-7 with alkali to obtain high-solids polycarboxylic acid slump retainer PCE3 with a solids content of 72%.

[0029] Example 4 (1) Place the reactor in an ice-water bath at 0-5℃, purge with nitrogen to remove oxygen, add 110g water, 725g tetrahydrofuran, 100g tea polyphenols and 88g potassium hydroxide, stir evenly, stir and heat to 35℃, slowly add 201g 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.

[0030] (2) Add 100g of 3-methyl-3-buten-1-polyethylene glycol with a molecular weight of 2400, 100g of 2-methylallyl polyethylene glycol with a molecular weight of 2400, 8g of bis(3-trimethoxysilylethyl)fumaric acid and 70g of water to a reaction vessel, heat to 20-40℃, stir until the polyether macromonomer is dissolved evenly, add 8g of the KZJ-ZR4 prepared above and 5.4g of sodium hypophosphite, and after the materials are mixed evenly, add unsaturated small monomers and unsaturated carboxyl groups dropwise. The mixture consists of esters (8g acrylic acid, 2g methacrylic acid, 18g hydroxyethyl acrylate, 6g hydroxypropyl acrylate and 2g ethylene glycol dimethacrylate) and an aqueous solution of ammonium persulfate (4.6g ammonium persulfate and 10g water). The addition time is 2.0h, the initial reaction temperature is 20-40℃, and the material temperature is controlled to be ≤60℃ during the addition process. After the addition is completed, the reaction continues for 1.0h, and then the pH is adjusted to 5-7 with alkali to obtain high solids content polycarboxylate superplasticizer PCE4 with a solids content of 79%.

[0031] 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. 102g of water, 756g of tetrahydrofuran, 100g of tea polyphenols and 108g of potassium hydroxide were added and stirred evenly. The mixture was stirred and heated to 40℃. 152g of 1,3-propanesulfonic acid lactone and 166g of 1,4-butanesulfonic acid lactone were slowly added dropwise over 1.0h. The reaction was continued to be stirred 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.

[0032] (2) Add 160g of 3-methyl-3-buten-1-polyethylene glycol with a molecular weight of 2400, 40g of 2-methylallyl polyethylene glycol with a molecular weight of 2400, 7g of bis(3-trimethoxysilylpropyl) fumarate, and 60g of water to a reaction vessel, heat to 20-40℃, and stir until the polyether macromonomer is dissolved evenly. Add 9g of the above-prepared KZJ-ZR5, 4g of sodium hypophosphite, and 1g of trisodium phosphate. After the materials are mixed evenly, add unsaturated small monomers and... Unsaturated carboxylic acid esters (12g acrylic acid, 20g hydroxyethyl acrylate, 5g hydroxyethyl methacrylate, 2g propylene glycol 1,3-dipropylene glycol) and ammonium persulfate aqueous solution (2.6g ammonium persulfate and 10g water) were added dropwise over 2.0h. The initial reaction temperature was 20-40℃, and the material temperature was controlled to be ≤60℃ during the dropwise addition. After the dropwise addition was completed, the reaction was continued for 1.0h, and then the pH was adjusted to 5-7 with alkali to obtain high-solids polycarboxylic acid slump retainer PCE5 with a solids content of 79%.

[0033] 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. 100g water, 666g tetrahydrofuran, 100g tea polyphenols and 80g potassium hydroxide were added and stirred evenly. The mixture was stirred and heated to 45℃. 286g 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.

[0034] (2) Add 80g of 3-methyl-3-buten-1-polyethylene glycol with a molecular weight of 2400, 120g of 2-methylallyl polyethylene glycol with a molecular weight of 2400, 6g of bis(3-trimethoxysilylethyl)fumaric acid and 60g of water to a reaction vessel, heat to 20-40℃, stir until the polyether macromonomer is dissolved evenly, add 8g of the above-prepared KZJ-ZR5, 2g of itaconic anhydride, 2g of sodium hypophosphite and 1.2g of sodium bisulfite, and after the materials are mixed evenly, drop... Unsaturated monomers and unsaturated carboxylic acid esters (11g acrylic acid, 15g hydroxyethyl acrylate, 2g hydroxypropyl acrylate, 1g glyceryl acrylate), and sodium persulfate aqueous solution (2.5g ammonium persulfate and 10g water) are added dropwise over 2.0h. The initial reaction temperature is 20-40℃, and the material temperature is controlled to ≤60℃ during the dropwise addition process. After the dropwise addition is completed, the reaction continues for 1.0h, and then the pH is adjusted to 5-7 with alkali to obtain high-solids polycarboxylic acid slump retainer PCE6 with a solids content of 78%.

[0035] Comparative Example 1 The commercially available product has a solid content of 60% and is designated as SPLY polycarboxylate superplasticizer Y1.

[0036] 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.

[0037] Comparative Example 3 Y3 was prepared by using the process of Example 1 as the basic process, without using water-locking and stabilizing small monomers for synthesis, while keeping other reaction conditions unchanged.

[0038] Comparative Example 4 Y4 was prepared by replacing KZJ-ZR1 with an equal amount of tea polyphenols, while keeping other reaction conditions unchanged.

[0039] Comparative Example 5 Based on the process in Example 1, Y5 was synthesized by replacing KZJ-ZR1 with alkyl sulfonate (sodium dodecyl sulfonate) while keeping other reaction conditions unchanged.

[0040] Comparative Example 6 Based on the process in Example 1, Y6 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.

[0041] 1. Solid content and viscosity test The solids content and viscosity of the high-solids-content polycarboxylate slump retainers 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.

[0042] Table 1 Viscosity test results

[0043] As shown in Table 1, the viscosity of all samples decreased with increasing temperature. The samples in Examples 1-6 had a solids content of 70-80% and low viscosity; their viscosity at 5°C was even lower than that of a commercially available product with 60% solids content at 40°C. This patented product still exhibits good flowability at low temperatures and can be pumped. Commercially available high-solids products and the comparative samples had higher viscosity, making pumping difficult and leading to pump wear. A comparison of PEC1 and Y1 shows that the solubilizer prepared by this patented invention has a significant effect on reducing the viscosity of the system.

[0044] 2. Concrete performance testing The concrete performance of the slump retainers prepared in Examples 1-6 and Comparative Examples 1-6 was tested. The samples obtained from the examples and comparative examples were mixed with PointTS8 at a ratio of 3:7 to prepare samples with 10% solid content. The concrete performance was tested at the same dosage. The test indicators included concrete spread, compressive strength, bleeding rate and concrete state at 0h, 2h and 4h. The test results are shown in Table 2.

[0045] Table 2 Concrete Test Results

[0046] As shown in Table 2, the products of this invention (PCE1-PCE6) are significantly superior to the comparative products (Y1-Y6) in terms of spread retention, bleeding rate control, and workability. Specifically, the products of this invention release smoothly, with stable spread (fluctuation range ≤50mm) within 0-4 hours, and virtually no bleeding, resulting in good concrete workability. In contrast, the comparative products not only suffer significant spread loss over time but also exhibit obvious delayed bleeding (bleeding rate up to 15.2%), leading to mediocre concrete workability. Specifically, the spread of Y1, Y2, Y3, and Y6 increases after 2 hours, showing a delayed increase, which is detrimental to concrete quality control. This indicates that the high-solids polycarboxylate slump stabilizer prepared by the solubilizer and water-locking stabilizer used in this invention not only has high solids content and low viscosity but also more effectively maintains the stability of concrete workability.

[0047] 3. Storage stability The high-solids polycarboxylate slump retainers 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 3.

[0048] Table 3 Storage stability test results

[0049] As shown in Table 3, compared with the comparative products (Comparative Examples 1 to 6), the patented products (Examples 1 to 6) exhibited 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 (except Y3) generally showed solidification, clumping, or stratification at low temperatures, and after long-term storage at high temperatures, they often showed off-odors and mold growth, demonstrating that the patented products have superior weather resistance and long-term storage stability. Furthermore, they can effectively inhibit microbial growth during storage in high-temperature environments, exhibiting certain anti-corrosion properties. In summary, the high-solids-content polycarboxylate slump retainer prepared in this invention successfully achieves a balance between high solids content and low viscosity. Its viscosity is significantly lower than other comparative examples at temperatures ranging from 5°C to 40°C, exhibiting excellent low-temperature fluidity and pumpability. Regarding concrete performance, the product of this invention maintains stable spread within 0-4 hours, exhibits virtually no bleeding, and demonstrates good workability, effectively overcoming problems such as delayed bleeding, significant water loss over time, or excessive hysteresis in existing products. Furthermore, the product shows no deterioration after 60 days of storage at both -10°C to 5°C and 40°C to 50°C, demonstrating excellent storage stability and inherent anti-corrosion properties.

[0050] 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.

[0051] 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 polycarboxylic acid slump retainer, 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 and the water-locking and slurry-stabilizing monomer are mixed and dissolved evenly with water, the prepared tea polyphenol-based polysulfonic acid solubilizer is added, and after mixing evenly, the unsaturated monomer, unsaturated carboxylic acid ester, 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 polycarboxylic acid slump retainer.

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 lactone; 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 small monomer, water-locking and sizing stabilizer small monomer, and unsaturated carboxylic acid ester is 200: (2-10): (2-15): (2-8): (10-35).

5. The preparation method according to claim 1, characterized in that: The water-locking and stabilizing monomer is one or more combinations of bis(3-trimethoxysilylpropyl) fumarate, bis(3-trimethoxysilylpropyl) maleate, and bis(3-trimethoxysilylethyl) fumarate.

6. The preparation method according to claim 1, characterized in that: The unsaturated carboxylic acid ester is one or more combinations of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl acrylate, glycidyl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol 1,3-diacrylate, pentylene glycol 1,5-dimethacrylate, and glycerol 1,3-diisobutylene ester.

7. The preparation method according to claim 1, characterized in that: The polyether macromonomer M is one or more of the following: 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. 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.

8. The preparation method according to claim 1, characterized in that: 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. 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.

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 and the water-locking and slurry-stabilizing monomer are 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, unsaturated carboxylic acid ester, 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 polycarboxylic acid slump retainer, characterized in that: It is prepared by the preparation method described in any one of claims 1-9.

Images