High-workability mud-resistant viscosity-reducing polycarboxylic acid water reducer as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of concrete, and discloses a preparation method of a high-workability mud-resistant viscosity reduction type polycarboxylic acid water reducer. The preparation method comprises the following steps: carrying out polymerization reaction on 120-260 parts by weight of a polyether monomer, 20-50 parts by weight of an unsaturated acid monomer, 3-10 parts by weight of a functional monomer, 3-6 parts by weight of an unsaturated amide monomer, 3-10 parts by weight of an esterification monomer, 0.8-1.5 parts by weight of a chain transfer agent, 0.5-2 parts by weight of an oxidant and 0.1-1 part by weight of a reducing agent, the functional monomer is a zwitterionic hybrid monomer with a boric acid group and a betaine group. According to the invention, the functional monomer, the unsaturated amide monomer and the esterification monomer are added into the water reducer and cooperate with each other, so that the expansion loss can be effectively reduced, the workability can be improved, the strength can be improved, and the application prospect is wide.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology and relates to a high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer, its preparation method, and its application. Background Technology

[0002] With the gradual depletion of natural high-quality sand and gravel resources, manufactured sand and recycled aggregates from construction waste have been widely used in concrete production, becoming the main aggregate source in the current concrete industry. However, compared with natural river sand, manufactured sand and recycled aggregates generally contain higher levels of clay minerals (such as montmorillonite and illite). These clay components have extremely strong surface adsorption capacity, which can adsorb a large number of traditional polycarboxylate superplasticizer (PCE) molecules, thereby significantly weakening the dispersing effect of the superplasticizer.

[0003] Because clay preferentially adsorbs water-reducing agents, the concentration of effective water-reducing agents in concrete mixtures decreases, leading to a sharp decline in their dispersion performance. This manifests as rapid loss of initial fluidity in fresh concrete, poor workability over time, high viscosity, and difficulty in pumping. It also easily causes bleeding and segregation, severely affecting the workability and construction performance of the concrete. These problems not only reduce the construction efficiency and project quality of concrete but also increase the difficulty of on-site control, becoming one of the key bottlenecks restricting the development of modern concrete technology.

[0004] To address the aforementioned issues, existing technologies have disclosed several polycarboxylate superplasticizers or modification techniques with anti-mud or viscosity-reducing functions. For example, some solutions introduce special functional groups such as phosphonic acid groups, amino groups, and sulfonic acid groups into the main chain or side chain of the superplasticizer to enhance its dispersion ability for cement particles or inhibit clay adsorption; other solutions employ compound thickeners, water-retaining agents, or viscosity modifiers to attempt to improve the water retention and workability of concrete. However, these existing technologies often have significant limitations in practical applications: on the one hand, while introducing specific anti-mud groups (such as phosphonic acid groups) can alleviate the clay adsorption problem to some extent, it may adversely affect the cement hydration process or the later-stage strength development of concrete; on the other hand, improving water retention by adding thickening substances often leads to a further increase in the viscosity of the concrete system, contradicting the engineering requirement of "viscosity reduction" and making it difficult to achieve overall optimization of workability.

[0005] Therefore, it is essential to develop a new type of high-efficiency, mud-resistant, viscosity-reducing polycarboxylate superplasticizer. Summary of the Invention

[0006] One of the objectives of this invention is to provide a novel polycarboxylate superplasticizer, which, when obtained by this method, combines low spread loss, good workability, and high strength.

[0007] The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer provided by the present invention includes a polymerization reaction of 120-260 parts by weight of polyether monomer, 20-50 parts by weight of unsaturated acid monomer, 3-10 parts by weight of functional monomer, 3-6 parts by weight of unsaturated amide monomer, 3-10 parts by weight of esterified monomer, 0.8-1.5 parts by weight of chain transfer agent, 0.5-2 parts by weight of oxidant, and 0.1-1 parts by weight of reducing agent; wherein the functional monomer is a zwitterionic hybrid monomer having boric acid group and betaine group.

[0008] Preferably, the polyether monomer contains both polyether monomer A and polyether monomer B.

[0009] Preferably, the mass ratio of polyether monomer A to polyether monomer B is 1:(0.5-1).

[0010] Preferably, the number average molecular weight of the polyether monomer A is 1000-1500, and the number average molecular weight of the polyether monomer B is 2500-3500.

[0011] Preferably, the unsaturated acid monomer is acrylic acid and / or methacrylic acid.

[0012] Preferably, the unsaturated amide monomer is N-isopropylacrylamide and / or N-vinylcaprolactam.

[0013] Preferably, the polymerization reaction is carried out in the presence of 0.8-1.5 parts by weight of chain transfer agent, 0.5-2 parts by weight of oxidant and 0.1-1 parts by weight of reducing agent.

[0014] Preferably, the chain transfer agent is selected from any one or a combination of at least two of mercaptoethanol, mercaptopropionic acid, and mercaptoacetic acid.

[0015] Preferably, the reducing agent is selected from any one or a combination of at least two of ascorbic acid, formaldehyde, sodium bisulfite and sodium hypophosphite.

[0016] Preferably, the oxidant is selected from any one or a combination of at least two of hydrogen peroxide, sodium persulfate, and ammonium persulfate.

[0017] Preferably, the functional unit has the structure of formula (I):

[0018] Formula (I).

[0019] Preferably, the method for preparing the functional monomer includes: A1. Styrene containing 4-trimethyl borate and pinacol is placed in a solvent and reacted at 50-70℃ for 1-3 h to obtain 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene. A2. Mix the 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene obtained in step A1 with 1-bromo-3-chloropropane and react at 70-90℃ for 10-14 h to obtain 4-vinylphenyl-3-chloropropane. A3. Add the 4-vinylphenyl-3-chloropropane obtained in step A2 and the aqueous solution of dimethylamine to the solvent and react at 40-60℃ for 5-7 h to obtain 4-vinylphenyl-3-(N,N-dimethylamino)propane. A4. The 4-vinylphenyl-3-(N,N-dimethylamino)propane obtained in step A3 is mixed with 1,3-propanesulfonyl lactone in a solvent and reacted at 50-70°C for 7-9 h to obtain a betaine hybrid intermediate protected by borate pinacol ester. A5. The betaine hybrid intermediate protected by borate pinacol ester obtained in step A4 is subjected to hydrolysis to obtain the functional monomer.

[0020] Preferably, the molar ratio of 4-boron trimethyl styrene to pinacol in step A1 is 1:(1-1.4).

[0021] Preferably, the molar ratio of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene to 1-bromo-3-chloropropane in step A2 is 1:(0.8-1.2).

[0022] Preferably, the molar ratio of 4-vinylphenyl-3-chloropropane added to the dimethylamine aqueous solution in step A3 is 1:(1-1.2).

[0023] Preferably, the molar ratio of 4-vinylphenyl-3-(N,N-dimethylamino)propane to 1,3-propanesulfonyl lactone in step A4 is 1:(1-1.2).

[0024] Preferably, the hydrolysis temperature in step A5 is 10-40℃, and the hydrolysis time is 30-90 min.

[0025] Preferably, the esterified monomer has the structure of formula (II): ; Formula (II); In equation (II), R is CH3(CH2). m , where 0 < m ≤ 7; 0 < n ≤ 5.

[0026] Preferably, the polymerization reaction includes the following steps: (1) Dissolve 120-260 parts by weight of polyether monomer in water and adjust the pH to 8-10 to form a premixed solution; (2) Dissolve 25-50 parts by weight of unsaturated acid monomer, 3-10 parts by weight of functional monomer, 3-6 parts by weight of unsaturated amide monomer and 3-10 parts by weight of esterified monomer in water to form drop solution A; dissolve 0.8-1.5 parts by weight of chain transfer agent and 0.1-1 parts by weight of reducing agent in water to form drop solution B; (3) Heat the premixed liquid obtained in step (1) to 10-15℃, add 0.5-2 parts by weight of oxidant, and then add the drop solution A and drop solution B prepared in step (2), and mature to obtain a high-strength and easy-to-use anti-mud and viscosity-reducing polycarboxylate superplasticizer.

[0027] Preferably, the addition time of the dripping solution A in step (3) is 40-60 min.

[0028] Preferably, the addition time of the dripping solution B in step (3) is 50-70 min.

[0029] Preferably, the ripening time in step (3) is 1-3 hours.

[0030] Preferably, step (3) further includes adjusting the pH of the matured mixture to 6-7 and adding water to adjust the solid content.

[0031] The second objective of this invention is to provide a product prepared by the above-described preparation method.

[0032] The third objective of this invention is to provide the application of the above-mentioned water-reducing agent in concrete.

[0033] Technical features and beneficial effects of the present invention: This invention utilizes zwitterionic hybrid monomers containing boric acid and betaine groups as functional monomers, unsaturated amide monomers, and esterification monomers in a water-reducing agent. The boric acid group forms stable BO-Al covalent bonds with clay minerals in an alkaline environment, achieving chemical anchoring. The betaine group, through its zwitterionic structure, generates electrostatic repulsion and steric hindrance, effectively inhibiting clay adsorption. The unsaturated amide monomer, relying on its thermosensitive properties, achieves reversible hydrophilicity / hydrophobicity transition in concrete, intelligently and dynamically adjusting viscosity to resolve the contradiction between high bleeding and high viscosity. After polymerization, the long-chain ether groups of the esterification monomer form a weak, dynamic three-dimensional hydrophilic network in the water-reducing agent. Under static conditions, this network effectively encapsulates free water, preventing water from rising and aggregate from settling, thereby completely eliminating bleeding and segregation, resulting in concrete with excellent cohesiveness and a "bright paste" effect. When subjected to shear forces (such as stirring or pumping), the network can be temporarily disrupted without significantly increasing flow resistance, achieving a perfect unity of the contradictory properties of "water retention and viscosity enhancement" and "viscosity reduction", giving concrete exceptional workability; through the combined effect of the three, it effectively resists clay adsorption while significantly reducing concrete viscosity, and endows the mixture with low spread loss, low bleeding rate, good workability and high strength. Detailed Implementation

[0034] In this invention, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the distribution of selectable values ​​within a numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this invention should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0035] The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing water-reducing agent provided by the present invention includes: polymerizing 120-260 parts by weight (e.g., 120 parts by weight, 150 parts by weight, 180 parts by weight, 200 parts by weight, 220 parts by weight, 250 parts by weight, 260 parts by weight, etc.) of polyether monomer, 25-50 parts by weight (e.g., 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, etc.) of unsaturated acid monomer, 3-10 parts by weight (e.g., 3 parts by weight, 5 parts by weight, 7 parts by weight, 10 parts by weight, etc.) of functional monomer, 3-6 parts by weight (e.g., 3 parts by weight, 5 parts by weight, 6 parts by weight, etc.) of unsaturated amide monomer, and 3-10 parts by weight of esterified monomer (e.g., 3 parts by weight, 5 parts by weight, 7 parts by weight, 10 parts by weight, etc.); wherein the functional monomer is an amphoteric hybrid monomer having boric acid group and betaine group.

[0036] This invention adds zwitterionic hybrid monomers with boric acid and betaine groups as functional monomers and N-isopropylacrylamide as thermosensitive monomers during the preparation of water-reducing agents. The boric acid groups can form stable BO-Al covalent bonds with clay minerals in an alkaline environment to achieve chemical anchoring; the betaine groups generate electrostatic repulsion and steric hindrance through their zwitterionic structure, effectively inhibiting clay adsorption through a dual effect.

[0037] This invention copolymerizes polyether monomers, unsaturated acid monomers, functional monomers, unsaturated amide monomers, and esterified monomers by adding specific amounts of these monomers. This effectively resists clay adsorption, significantly reduces concrete viscosity, and imparts excellent cohesiveness, water retention, and pumpability to the mixture.

[0038] In some embodiments, the polyether monomer contains both polyether monomer A and polyether monomer B.

[0039] In some embodiments, the mass ratio of polyether monomer A to polyether monomer B is 1:(0.5-1), such as 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.

[0040] In some embodiments, the number average molecular weight of the polyether monomer A is 1000-1500, such as 1000, 1100, 1200, 1300, 1400, 1500, etc.; and the number average molecular weight of the polyether monomer B is 2500-3500, such as 2500, 2800, 3000, 3200, 3500, etc.

[0041] In this invention, two polyether monomers with specific molecular weight ranges are blended in a mass ratio of 1:(0.5-1) to form a gradient steric hindrance system. The lower molecular weight polyether monomer has a faster diffusion and adsorption rate and is mainly responsible for providing the initial dispersive force; the higher molecular weight polyether monomer can form a thicker and more stable hydration layer, providing strong and durable steric hindrance, effectively maintaining the slump retention of concrete. The synergy of the two overcomes the shortcomings of single molecular weight polyether side chains in achieving both dispersibility and durability.

[0042] In some embodiments, the unsaturated acid monomer is acrylic acid and / or methacrylic acid.

[0043] In some embodiments, the unsaturated amide monomer is N-isopropylacrylamide and / or N-vinylcaprolactam.

[0044] In this invention, by introducing unsaturated amide monomers and utilizing their temperature-sensitive properties, a reversible hydrophilic-hydrophobic transition can be achieved in concrete, thereby intelligently and dynamically adjusting the viscosity, simultaneously resolving the contradiction between high bleeding and high viscosity, and significantly improving construction performance.

[0045] In some embodiments, the polymerization reaction is carried out in the presence of 0.8-1.5 parts by weight (e.g., 0.8 parts by weight, 1 part by weight, 1.2 parts by weight, 1.5 parts by weight, etc.) of a chain transfer agent, 0.5-2 parts by weight (e.g., 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, etc.) of an oxidant, and 0.1-1 parts by weight (e.g., 0.1 parts by weight, 0.3 parts by weight, 0.5 parts by weight, 0.7 parts by weight, 1 part by weight, etc.) of a reducing agent.

[0046] In some embodiments, the chain transfer agent is selected from any one or a combination of at least two of mercaptoethanol, mercaptopropionic acid, and mercaptoacetic acid.

[0047] In some embodiments, the reducing agent is selected from any one or a combination of at least two of ascorbic acid, formaldehyde, sodium bisulfite, and sodium hypophosphite.

[0048] In some embodiments, the oxidant is selected from any one or a combination of at least two of hydrogen peroxide, sodium persulfate, and ammonium persulfate.

[0049] In some embodiments, the functional unit has the following structure (I):

[0050] Formula (I).

[0051] In this invention, a functional monomer with the structure of formula (I) is used. This monomer achieves high efficiency anti-mud through a dual mechanism of chemical anchoring and physical shielding. In this monomer, the boric acid group specifically coordinates with the aluminum hydroxyl groups (Al-OH) between clay minerals (such as montmorillonite) in the alkaline environment of cement paste to form a stable BO-Al covalent bond, which preemptively occupies the active adsorption sites of clay. The betaine group, as a zwitterion, physically blocks the water-reducing agent molecular chains from inserting into the clay layers through strong hydration and steric hindrance. The two work synergistically to fundamentally inhibit the adsorption of polycarboxylic acid molecules by clay, ensuring the effective adsorption amount on cement particles.

[0052] In some embodiments, the method for preparing the functional monomer includes: A1. 4-Trimethyl 4-borate styrene and pinacol are placed in a solvent and reacted at 50-70℃ (e.g., 50℃, 55℃, 60℃, 65℃, 70℃, etc.) for 1-3 h (e.g., 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc.) to obtain 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene; A2. The 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboron-2-yl)styrene obtained in step A1 is mixed with 1-bromo-3-chloropropane and reacted at 70-90℃ (e.g., 70℃, 75℃, 80℃, 85℃, 90℃, etc.) for 10-14 h (e.g., 10 h, 11 h, 12 h, 13 h, 14 h, etc.) to obtain 4-vinylphenyl-3-chloropropane; A3. Add the 4-vinylphenyl-3-chloropropane obtained in step A2 and the aqueous solution of dimethylamine to a solvent and react at 40-60℃ (e.g., 40℃, 45℃, 50℃, 55℃, 60℃, etc.) for 5-7 h (e.g., 5 h, 5.5 h, 6 h, 6.5 h, 7 h, etc.) to obtain 4-vinylphenyl-3-(N,N-dimethylamino)propane; A4. The 4-vinylphenyl-3-(N,N-dimethylamino)propane obtained in step A3 is mixed with 1,3-propanesulfonyl lactone in a solvent and reacted at 50-70°C (e.g., 50°C, 55°C, 60°C, 65°C, 70°C, etc.) for 7-9 h (e.g., 7 h, 7.5 h, 8 h, 8.5 h, 9 h, etc.) to obtain a betaine hybrid intermediate protected by borate pinacol ester; A5. The betaine hybrid intermediate protected by borate pinacol ester obtained in step A4 is subjected to hydrolysis to obtain the functional monomer.

[0053] In some embodiments, the molar ratio of 4-boron trimethyl styrene to pinacol in step A1 is 1:(1-1.4), such as 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, etc.

[0054] In some embodiments, the solvent in step A1 is toluene.

[0055] In some embodiments, the molar ratio of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene to 1-bromo-3-chloropropane in step A2 is 1:(0.8-1.2), for example 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, etc.

[0056] In some embodiments, the reaction in step A2 is carried out under the action of a catalyst and a base, wherein the catalyst is tetraphenylphosphine palladium and the base is potassium carbonate.

[0057] In some embodiments, the molar ratio of 4-vinylphenyl-3-chloropropane added to dimethylamine in the aqueous dimethylamine solution in step A3 is 1:(1-1.2), such as 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, etc.

[0058] In some embodiments, the solvent in step A3 is ethanol.

[0059] In some embodiments, the molar ratio of 4-vinylphenyl-3-(N,N-dimethylamino)propane to 1,3-propanesulfonyl lactone in step A4 is 1:(1-1.2), for example 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, etc.

[0060] In some embodiments, the solvent in step A4 is acetonitrile.

[0061] In some embodiments, the hydrolysis reaction in step A5 is carried out in an acidic solution with a pH of 5-6.

[0062] In some embodiments, the hydrolysis temperature in step A5 is 10-40°C, such as 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, etc.; the hydrolysis time is 30-90 min, such as 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, etc.

[0063] In some embodiments, step A5 further includes sequentially performing solid-liquid separation and purification on the mixture obtained from the hydrolysis reaction.

[0064] In some embodiments, the esterified monomer has the structure of formula (II): Formula (II); In equation (II), R is CH3(CH2). m , where 0 < m ≤ 7 (e.g., 1, 2, 3, 4, 5, 6, 7); 0 < n ≤ 5 (e.g., 1, 2, 3, 4, 5).

[0065] In this invention, the esterification monomer is a workability-improving monomer prepared by esterification of maleic anhydride and glycol ether. After polymerization, the long-chain ether structure of this monomer can form a weak, dynamic three-dimensional hydrophilic network in the slurry. Under static conditions, this network can effectively encapsulate free water, preventing water from rising and aggregate from settling, thereby completely eliminating bleeding and segregation, giving the concrete excellent cohesiveness and a "bright slurry" effect. When subjected to shear forces (such as stirring or pumping), this network can be temporarily destroyed without significantly increasing flow resistance, achieving a perfect unity of the contradictory properties of "water retention and viscosity enhancement" and "viscosity reduction," endowing the concrete with exceptional workability.

[0066] In some embodiments, the preparation method of the esterified monomer includes: mixing maleic anhydride and polyethylene glycol alkyl ether at a molar ratio of 1:(1.0-1.2), and reacting at 80-95°C (e.g., 80°C, 85°C, 90°C, 95°C, etc.) for 3-5 h (e.g., 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc.) to obtain the esterified monomer.

[0067] In some embodiments, the polymerization reaction includes the following steps: (1) Dissolve 120-260 parts by weight of polyether monomer in water and adjust the pH to 8-10 (e.g., 8, 8.5, 9, 9.5, 10, etc.) to form a premixed solution; (2) Dissolve 25-50 parts by weight of unsaturated acid monomer, 3-10 parts by weight of functional monomer, 3-6 parts by weight of unsaturated amide monomer and 3-10 parts by weight of esterified monomer in water to form drop solution A; Dissolve 0.8-1.5 parts by weight of chain transfer agent and 0.1-1 parts by weight of reducing agent in water to form drop solution B; (3) Heat the premixed liquid obtained in step (1) to 10-15℃ (e.g., 10℃, 12℃, 15℃, etc.), add 0.5-2 parts by weight of oxidant, and then add the drop liquid A and drop liquid B prepared in step (2), and mature to obtain a high and easy-to-use anti-mud and viscosity-reducing polycarboxylate superplasticizer.

[0068] The preparation method provided by this invention is simple and easy to implement for large-scale production and application.

[0069] It should be noted that there is no sequential relationship between steps (1) and (2) in the actual preparation process. Step (1) can be prepared first, or step (2) can be prepared first. Similarly, there is no sequential relationship between the preparation of drop solution A and drop solution B in step (2). Drop solution A can be prepared first, or drop solution B can be prepared first.

[0070] In some embodiments, the addition time of the droplet A in step (3) is 40-60 min (e.g., 40 min, 45 min, 50 min, 55 min, 60 min, etc.).

[0071] In some embodiments, the addition time of the droplet B in step (3) is 50-70 min (e.g., 50 min, 55 min, 60 min, 65 min, 70 min, etc.).

[0072] In some embodiments, the curing time in step (3) is 1-3 h (e.g., 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc.).

[0073] In some embodiments, step (3) further includes adjusting the pH of the matured mixture to 6-7 (e.g., 6, 6.2, 6.5, 6.8, 7, etc.) and adding water to adjust the solid content.

[0074] The present invention will be described in detail below through embodiments.

[0075] Preparation Example 1 This preparation example provides a method for preparing a functional monomer, which is a functional monomer with the structure of formula (I). The preparation method includes: A1, Boric acid group protection: To a 250 mL three-necked round-bottom flask equipped with a condenser, thermometer, and magnetic stirrer, 19.2 g (0.10 mol) of trimethyl 4-borate styrene, 14.2 g (0.12 mol) of pinacol, and 150 mL of anhydrous toluene were added. The reaction mixture was stirred in an oil bath at 60 °C for 2 hours under a nitrogen atmosphere. After the reaction was complete, the reaction mixture was transferred to a rotary evaporator, and the toluene solvent was removed by vacuum distillation to obtain 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene.

[0076] A2. Suzuki coupling introduces active sites: To the product obtained in the previous step (20.7 g, 0.08 mol), 1-bromo-3-chloropropane (13.7 g, 0.08 mol), tetratetraphenylphosphine palladium (1.85 g, 1.6 mmol), potassium carbonate (22.1 g, 0.16 mol), 120 mL of tetrahydrofuran, and 30 mL of water were added. The system was subjected to three cycles of vacuum-nitrogen purging to replace the inert gas, and then the reaction was stirred in an oil bath at 80 °C under nitrogen protection for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, and the insoluble matter was removed by filtration. The filtrate was extracted with ethyl acetate (100 mL × 3). The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 10 / 1, v / v) to give 4-vinylphenyl-3-chloropropane.

[0077] A3. Tertiary amination reaction: The 4-vinylphenyl-3-chloropropane (12.8 g, 0.064 mol) obtained in the previous step and 40% dimethylamine aqueous solution (7.1 g, 0.063 mol, based on pure dimethylamine) were added to 100 mL of anhydrous ethanol. The reaction was stirred in a water bath at 50 °C for 6 hours. After the reaction was completed, the ethanol and excess dimethylamine were removed by vacuum distillation to obtain 4-vinylphenyl-3-(N,N-dimethylamino)propane.

[0078] A4. Construction of the betaine structure: The tertiary amine product obtained in the previous step (12.1 g, 0.058 mol) and 1,3-propanesulfonyl lactone (7.8 g, 0.064 mol) were dissolved in 80 mL of acetonitrile. The reaction was stirred in an oil bath at 60 °C for 8 hours. A white solid precipitated during the reaction. After the reaction was completed, the mixture was cooled and filtered. The solid was washed with cold acetonitrile to obtain a white powdery betaine hybrid intermediate protected by pinacol borate ester.

[0079] A5. Hydrolysis and purification: The intermediate obtained in the previous step (17.2 g, 0.052 mol) was suspended in 150 mL of dilute hydrochloric acid aqueous solution with pH=5.5 and hydrolyzed by stirring at 25 °C for 1 hour. After hydrolysis, the solution became homogeneous. The pH was carefully adjusted to neutral with saturated sodium bicarbonate solution, and then most of the water was removed by concentration under reduced pressure using a rotary evaporator. The resulting viscous substance was recrystallized from the ethanol / acetone mixture to obtain the target functional monomer.

[0080] The structure of this functional monomer was identified by ¹H NMR and infrared spectroscopy, and it was found to be consistent with formula (I).

[0081] Preparation Example 2 This preparation example provides a method for preparing a functional monomer, including: A1, Boric acid group protection: 0.10 mol of 4-boron trimethyl styrene and 0.10 mol of pinacol were added to toluene and reacted at 50 °C for 1 hour. The post-treatment was the same as in Preparation Example 1 to obtain the intermediate.

[0082] A2. Suzuki coupling introduces active sites: The product from step A1 (0.08 mol) was reacted with 1-bromo-3-chloropropane (0.064 mol, molar ratio 1:0.8) at 70 °C for 10 hours. Post-treatment was the same as in Preparation Example 1.

[0083] A3. Tertiary amination reaction: The reaction was carried out at 40°C using ethanol as a solvent for 5 hours. Post-treatment was the same as in Preparation Example 1.

[0084] A4. Construction of the betaine structure: The reaction was carried out at 50°C using acetonitrile as a solvent for 7 hours. Post-treatment was the same as in Preparation Example 1.

[0085] A5. Hydrolysis and purification: The target functional monomer was hydrolyzed in a dilute hydrochloric acid aqueous solution at pH 5 for 30 minutes at 10°C. After purification, the monomer was obtained.

[0086] The structure of this functional monomer was identified by ¹H NMR and infrared spectroscopy, and it was found to be consistent with formula (I).

[0087] Preparation Example 3 This preparation example provides a method for preparing a functional monomer, including: A1, Boric acid group protection: 0.10 mol of trimethyl 4-borate styrene and 0.14 mol of pinacol were added to toluene and reacted at 70 °C for 3 hours. The post-treatment was the same as in Preparation Example 1 to obtain the intermediate.

[0088] A2. Suzuki coupling introduces active sites: The product from step A1 (0.08 mol) was reacted with 1-bromo-3-chloropropane (0.096 mol, molar ratio 1:1.2) at 90 °C for 14 hours. Post-treatment was the same as in Preparation Example 1.

[0089] A3. Tertiary amination reaction: The reaction was carried out at 60°C using ethanol as a solvent for 7 hours. Post-treatment was the same as in Preparation Example 1.

[0090] A4. Construction of the betaine structure: The reaction was carried out at 70°C using acetonitrile as a solvent for 9 hours. Post-treatment was the same as in Preparation Example 1.

[0091] A5. Hydrolysis and purification: The target functional monomer was hydrolyzed in a dilute hydrochloric acid aqueous solution at pH 6 for 90 minutes at 40°C. After purification, the monomer was obtained.

[0092] The structure of this functional monomer was identified by ¹H NMR and infrared spectroscopy, and it was found to be consistent with formula (I).

[0093] Example 1 The raw materials for the high-strength, easy-to-use, mud-resistant, and viscosity-reducing carboxylic acid superplasticizer provided in this embodiment include: 100 parts by weight of isopentenyl polyoxyethylene monomer (A1) with a number average molecular weight of 1100, 50 parts by weight of isopentenyl polyoxyethylene monomer (A2) with a number average molecular weight of 3000, 30 parts by weight of unsaturated acid monomer (B), 5 parts by weight of functional monomer (C, obtained from Preparation Example 1), 2.5 parts by weight of unsaturated amide monomer (D), 5 parts by weight of esterified monomer (E, having the structure shown in Formula (II), where n=1, m=3), 0.8 parts by weight of chain transfer agent (F), 1.5 parts by weight of oxidant (G), and 0.3 parts by weight of reducing agent (H). The unsaturated acid monomer is methacrylic acid, the functional monomer is the functional monomer obtained in Preparation Example 1, the esterified monomer is the esterified monomer obtained in Preparation Example 4, the oxidant is hydrogen peroxide, and the reducing agent is ascorbic acid.

[0094] The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer provided in this embodiment includes: (1) Preparation of premixed solution: 100 parts of unsaturated polyether macromonomer A1 and 50 parts of A2 are added to the reactor, 300 parts of water are added to the reactor, dissolved evenly, and the pH of the solution is adjusted to alkaline 9 with sodium hydroxide to obtain the premixed solution.

[0095] (2) Preparation of the dropping solution: Adjust the temperature of the premixed solution to 12℃. Prepare dropping solution A: Dissolve 30 parts of unsaturated carboxylic acid monomer B, 5 parts of boric acid-betaine hybrid monomer C, 2.5 parts of unsaturated amide monomer D, and esterified monomer E in 50 parts of water to obtain dropping solution A. Prepare dropping solution B: Mix 0.3 parts of reducing agent and 0.3 parts of chain transfer agent evenly to obtain dropping solution B.

[0096] (3) Polymerization stage: Add 1.5 parts of oxidant to the premixed solution and stir evenly. Add drop solution A and drop solution B at a uniform rate for 50 min and 60 min respectively. Control the temperature of the polymerization process to not exceed 35℃.

[0097] (4) Heat preservation and maturation: After the dripping is completed, heat preservation and maturation for 1.5 h.

[0098] (5) Post-treatment: After the heat preservation is completed, adjust the pH value to 6.0-7.0 with alkaline solution, add water to adjust to the required solid content, and you will get the high-efficiency, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer.

[0099] Example 2 The high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer was prepared according to the method of Example 1, except that the esterified monomer E had the structure shown in formula (II), n=1, m=5, and the amount of substance was varied to obtain the high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer.

[0100] Example 3 The high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer was prepared according to the method of Example 1, except that the functional monomer was obtained from Preparation Example 2, the esterified monomer E had the structure shown in Formula (II), n=1, m=5, and the amount of substance was varied to obtain the high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer.

[0101] Example 4 The high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer was prepared according to the method of Example 1, except that the functional monomer was obtained from Preparation Example 3, the esterified monomer E had the structure shown in Formula (II), n=2, m=3, and the amount of substance was varied to obtain the high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer.

[0102] Example 5 A high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer was prepared according to the method of Example 1, except that the polyether macromonomer A2 was replaced by the same amount of polyether macromonomer A1 by weight, and the other conditions were the same as in Example 1, thus obtaining a high-strength, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer.

[0103] Comparative Example 1 A polycarboxylate superplasticizer was prepared according to the method of Example 1, except that the polyether macromonomer A1 was replaced by the same amount of polyether macromonomer A2, and monomers C, D and E were not added, and the amount of substances was varied to obtain a reference polycarboxylate superplasticizer.

[0104] Comparative Example 2 A reference polycarboxylate superplasticizer was prepared according to the method of Example 1, except that monomer E was not added, while the other conditions were the same as in Example 1.

[0105] Comparative Example 3 A reference polycarboxylate superplasticizer was prepared according to the method of Example 1, except that monomer C was not added, while the other conditions were the same as in Example 1.

[0106] Table 1

[0107] Test case The water-reducing agents prepared in Examples 1-5 and Comparative Examples 1-3 were applied to cement tests. The cement used was Runfeng cement (P·O42.5). By adjusting the dosage of the water-reducing agent, when the concrete spread was (610±10) mm, the effects of the water-reducing agent on the initial and 1.0-hour slump, initial and 1.0-hour spread, 0-hour and 1.0-hour inverted slump cylinder emptying time, compressive strength at various ages, and bleeding rate were tested according to GB 8076-2008 "Concrete Admixtures". The mix proportion of the base concrete (i.e., cementitious material) was: cement 380 kg / m³. 3 70 kg / m³ of fly ash 3 70% mineral powder, 759 kg / m³ manufactured sand 3 Small stones 201 kg / m 3 Large rocks 800 kg / m 3 145 kg / m³ of water 3 The water-reducing agent was a composite water-reducing agent obtained by compounding a standard polycarboxylate water-reducing agent (Point-TBS from Kezhijie New Materials Group Co., Ltd.) with the polycarboxylate water-reducing agents obtained in the above examples or comparative examples at a mass ratio of 1:1. The concrete test results are shown in Table 2.

[0108] Table 2 (containing 5% mud)

[0109] Here, slump (initial, 1h) refers to the initial slump and the slump after 1 hour; similarly, spread (initial, 1h) refers to the initial spread and the spread after 1 hour; and inverted venting time (initial, 1h) refers to the initial inverted venting time and the initial inverted venting time after 1 hour.

[0110] As can be seen from the data in Table 2 comparing the examples and embodiments: In manufactured sand concrete with a mud content of 5%, Comparative Example 1 (traditional PCE) lacked anti-mud, viscosity-reducing, and workability-enhancing components. At a dosage of 0.25%, the spread loss was 180 mm in 1.0 h, the air-draining time was 16.8 s, the bleeding rate was as high as 4%, the mixture had poor encapsulation, and the 3-day strength was only 47.6 MPa, and the 28-day strength was 68.3 MPa. This reflects that clay adsorption led to dispersion failure and inhibited hydration.

[0111] Comparative Example 2 (lacking monomer E) showed a spread loss of 90 mm in 1.0 h, but emptying time was 13.5 s and the water bleeding rate was as high as 3%, indicating poor workability. At the same time, the mixture was viscous and the 3-day strength was 49.8 MPa. The lack of temperature-sensitive viscosity reduction resulted in high pumping resistance.

[0112] Comparative Example 3 (lacking monomer C) showed a spread loss of 120 mm in 1.0 h, an emptying time of 15.2 s, poor water seepage and encapsulation, and a 3-day strength of 48.9 MPa, highlighting the contradiction between water retention and cohesion.

[0113] In contrast, Example 1 (PCE-1#) with a dosage of only 0.22% reduced the spread loss to 20 mm in 1.0 h, emptied in 9.1 s, produced a full slurry with good encapsulation, no bleeding or segregation, and achieved a 3-day strength of 51.9 MPa and a 28-day strength of 72.5 MPa, achieving a synergistic effect of three benefits.

[0114] Example 2 (PCE-2#) has a 1.0h drainage time of only 8.8 s, full slurry with good encapsulation, no bleeding or segregation, and a 28-day strength of up to 73.0 MPa, with the best anti-mud and viscosity reduction.

[0115] Example 3 (PCE-3#) showed a spread loss of only 10 mm in 1.0 h and an emptying time of only 8.6 s in 1.0 h. The slurry was full, had good encapsulation, no bleeding or segregation, and was fine with a fast flow rate and good encapsulation, indicating excellent workability.

[0116] Example 4 (PCE-4#) showed a spread loss of only 15 mm in 1.0 h and an emptying time of only 8.9 s in 1.0 h. The slurry was full, had good encapsulation, no bleeding or segregation, and was fine with a fast flow rate, indicating excellent workability. At the same time, the 7-day strength was as high as 61.2 MPa, indicating long-term dispersion.

[0117] Example 5 (PCE-4#) uses only the monomer polyether macromonomer. The 1.0h spread loss is relatively large, at 75 mm, and the evacuation time is also extended to 12.9 s. The surface slurry indicates that the workability is lower than that of Example 1. At the same time, the 3-day strength is 50.5 MPa, indicating that the dispersion performance is lower than that of Example 1.

[0118] In summary, Comparative Examples 1-3 suffered from a chain-like performance degradation due to the lack of monomers, while Examples 1-5, through precise control of the water-reducing agent formulation with specific content, constructed a closed-loop system in high-mud-content aggregates with low expansion loss, low bleeding rate, good workability, and high strength.

[0119] It should also be noted that the above are merely preferred embodiments of the present invention and do not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for preparing a high-efficiency, mud-resistant, viscosity-reducing polycarboxylate superplasticizer, characterized in that, The preparation method includes: polymerizing 120-260 parts by weight of polyether monomer, 20-50 parts by weight of unsaturated acid monomer, 3-10 parts by weight of functional monomer, 3-6 parts by weight of unsaturated amide monomer, and 3-10 parts by weight of esterified monomer; wherein the functional monomer is a zwitterionic hybrid monomer having boric acid group and betaine group.

2. The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The polyether monomer contains both polyether monomer A and polyether monomer B. The mass ratio of polyether monomer A to polyether monomer B is 1:(0.5-1); The number average molecular weight of the polyether monomer A is 1000-1500, and the number average molecular weight of the polyether monomer B is 2500-3500. The unsaturated acid monomer is acrylic acid and / or methacrylic acid; The unsaturated amide monomer is N-isopropylacrylamide and / or N-vinylcaprolactam.

3. The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The polymerization reaction is carried out in the presence of 0.8-1.5 parts by weight of chain transfer agent, 0.5-2 parts by weight of oxidant and 0.1-1 parts by weight of reducing agent; The chain transfer agent is selected from any one or a combination of at least two of mercaptoethanol, mercaptopropionic acid and mercaptoacetic acid; The reducing agent is selected from any one or a combination of at least two of ascorbic acid, formaldehyde, sodium bisulfite and sodium hypophosphite; The oxidant is selected from any one or a combination of at least two of hydrogen peroxide, sodium persulfate, and ammonium persulfate.

4. The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The functional unit has the following structure (I): Formula (I).

5. The preparation method of the high-strength, easy-to-use, mud-resistant, viscosity-reducing polycarboxylate superplasticizer according to any one of claims 1-4, characterized in that, The preparation method of the functional monomer includes: A1. Styrene containing 4-trimethyl borate and pinacol is placed in a solvent and reacted at 50-70℃ for 1-3 h to obtain 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene. A2. Mix the 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene obtained in step A1 with 1-bromo-3-chloropropane and react at 70-90℃ for 10-14 h to obtain 4-vinylphenyl-3-chloropropane. A3. Add the 4-vinylphenyl-3-chloropropane obtained in step A2 and the aqueous solution of dimethylamine to the solvent and react at 40-60℃ for 5-7 h to obtain 4-vinylphenyl-3-(N,N-dimethylamino)propane. A4. The 4-vinylphenyl-3-(N,N-dimethylamino)propane obtained in step A3 is mixed with 1,3-propanesulfonyl lactone in a solvent and reacted at 50-70℃ for 7-9 h to obtain a betaine hybrid intermediate protected by borate pinacol ester. A5. The betaine hybrid intermediate protected by borate pinacol ester obtained in step A4 is subjected to hydrolysis to obtain the functional monomer.

6. The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer according to claim 5, characterized in that, The molar ratio of 4-boron trimethyl styrene to pinacol in step A1 is 1:(1-1.4); The molar ratio of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)styrene to 1-bromo-3-chloropropane in step A2 is 1:(0.8-1.2). The molar ratio of 4-vinylphenyl-3-chloropropane to dimethylamine in step A3 is 1:(1-1.2); The molar ratio of 4-vinylphenyl-3-(N,N-dimethylamino)propane to 1,3-propanesulfonyl lactone in step A4 is 1:(1-1.2). The hydrolysis temperature in step A5 is 10-40℃, and the hydrolysis time is 30-90 min.

7. The preparation method of the high-strength, easy-to-use, mud-resistant, viscosity-reducing polycarboxylate superplasticizer according to any one of claims 1-4, characterized in that, The esterified monomer has the following structure (II): Formula (II); In equation (II), R is CH3(CH2). m , where 0 < m ≤ 7; 0 < n ≤ 5.

8. The preparation method of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer according to any one of claims 1-7, characterized in that, The polymerization reaction includes the following steps: (1) Dissolve 120-260 parts by weight of polyether monomer in water and adjust the pH to 8-10 to form a premixed solution; (2) Dissolve 25-50 parts by weight of unsaturated acid monomer, 3-10 parts by weight of functional monomer, 3-6 parts by weight of unsaturated amide monomer and 3-10 parts by weight of esterified monomer in water to form drop solution A; dissolve 0.8-1.5 parts by weight of chain transfer agent and 0.1-1 parts by weight of reducing agent in water to form drop solution B; (3) Heat the premixed liquid obtained in step (1) to 10-15℃, add 0.5-2 parts by weight of oxidant, and then add the drop solution A and drop solution B prepared in step (2), and mature to obtain a high-strength and easy-to-use anti-mud and viscosity-reducing polycarboxylate superplasticizer.

9. A high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer prepared by the method according to any one of claims 1-8.

10. The application of the high-strength, easy-to-use, mud-resistant, and viscosity-reducing polycarboxylate superplasticizer according to claim 9 in concrete.

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