High-performance super-early-strength polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention discloses a high-performance super-early-strength polycarboxylic acid water reducing agent and a preparation method of the high-performance super-early-strength polycarboxylic acid water reducing agent, and relates to the technical field of concrete admixtures. And polymerizing polyethylene glycol divinyl ether, acrylic acid, a monomer s and methacrylic acid-2-hydroxyethyl ester phosphate to obtain the water-based acrylic acid water-based acrylic acid water-based acrylic acid water-based acrylic acid water-based acrylic acid water-based acrylic acid. The raw materials such as the acrylic acid, the monomer s and the methacrylic acid-2-hydroxyethyl phosphate are combined, so that the polycarboxylic acid water reducer can be endowed with good early strength performance and mud resistance.

Description

Technical Field

[0001] This invention relates to the field of concrete admixtures, specifically to a high-performance ultra-early-strength polycarboxylate superplasticizer and its preparation method. Background Technology

[0002] With the development of concrete preparation technology, higher requirements have been placed on the various properties of concrete. Correspondingly, the research and production of concrete admixtures are also developing towards environmental protection and high performance. Water-reducing agents are the most widely used and consumed type of concrete admixture. Adding water-reducing agents to fresh concrete can disrupt the flocculated structure of cement particles, thereby dispersing cement particles and hydrating cement particles, releasing free water from the flocculated structure, and increasing the flowability and dispersibility of the concrete mixture. Research on polycarboxylate water-reducing agents has become a hot topic in the research and development of concrete admixtures both domestically and internationally.

[0003] However, in practical applications, ordinary polycarboxylate superplasticizers significantly delay cement hydration, especially in cold environments (such as 0-5℃). The hydration reaction rate decreases, the superplasticizer adsorption layer becomes denser and more stable, further inhibiting CSH (calcium silicate hydrate) gel nucleation, resulting in slow early strength development in concrete. This limits its use in concrete requiring high early strength. Currently, commonly used concrete early strength agents include chloride-based, sulfate-based, carbonate-based, organic-based, mineral-based, and composite early strength agents. However, existing early strength agents easily introduce chloride ions or alkali metals into concrete. Whether it's chloride-induced steel corrosion or excessive alkali metals causing aggregate reaction, both can lead to structural damage in concrete.

[0004] Therefore, how to develop early-strength monomers that combine efficient dispersion and hydration promotion functions, so that the resulting polycarboxylate superplasticizer can still effectively improve the early strength of concrete in cold environments, requires further research. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a high-performance ultra-early strength polycarboxylate superplasticizer and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a high-performance ultra-early strength polycarboxylate superplasticizer includes the following steps:

[0008] Step A1: Mix and stir the nitroimidazole-containing aqueous ethanol solution, add the reducing agent, heat and stir to obtain product a1;

[0009] Step A2: After mixing and stirring product a1, ethyl acetate and epichlorohydrin, tetrabutylammonium bromide is added, reflux is turned on, and the mixture is heated and stirred. After cooling to room temperature, alkali solution is added, and stirring is continued to obtain product a2.

[0010] Step A3: Mix product a2, sodium aminonaphthalene sulfonate, and ethanol, stir, add triethylamine, heat and stir to obtain product a3;

[0011] Step A4: Mix and stir the terminal alkenyl carboxylic acid and acetonitrile, place in an ice-water bath, add HOAt, stir, add EDC, continue stirring, add catalyst and product a3, heat to room temperature, and stir to obtain product a4; under a protective gas, mix product a4, haloalkoxysilane and anhydrous ethanol, heat and stir to obtain monomer s;

[0012] Step A5: Mix polyethylene glycol divinyl ether and deionized water to obtain mixture 1; mix acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water to obtain mixture 2; mix ascorbic acid, mercaptoacetic acid, and deionized water to obtain mixture 3; mix mixture 1 and hydrogen peroxide solution, then add mixture 2 and mixture 3 sequentially while stirring, continue stirring, cool, and adjust the pH to obtain a high-performance ultra-early strength polycarboxylate superplasticizer.

[0013] Furthermore, the preparation method of the high-performance ultra-early strength polycarboxylate superplasticizer includes the following specific steps:

[0014] Step A1: Mix and stir the nitroimidazole-containing aqueous ethanol solution for 25-30 min, add the reducing agent, heat to 50-60℃, stir and react for 3-4 h, adjust the pH to 4.5-5 with hydrochloric acid solution, extract with ethyl acetate, adjust the pH of the aqueous phase to 9-10, extract with ethyl acetate again, collect the organic phase, wash with saturated sodium chloride solution, dry with anhydrous sodium sulfate, filter, and rotary evaporate to obtain product a1;

[0015] Furthermore, the ratio of the amount of nitroimidazole, aqueous ethanol solution, and reducing agent is 7.5-8.5g: 35-45mL: 9.5-10.5g; the nitroimidazole is 1,2-dimethyl-5-nitroimidazole; and the reducing agent is sodium dithionite.

[0016] Furthermore, the ethanol-water solution is obtained by mixing ethanol and water in a volume ratio of 1-2:1, and adjusting the pH to 8-9 with sodium bicarbonate; the volume fraction of ethanol is 95%.

[0017] In step A1, the nitro group in the nitroimidazole is reduced to an amino group to obtain product a1;

[0018] Step A2: Mix product a1, ethyl acetate, and epichlorohydrin and stir for 10-20 min. Add tetrabutylammonium bromide, turn on reflux, heat to 90-100℃, stir for 3-4 h, cool to room temperature, add alkaline solution, continue stirring for 2-2.5 h, add deionized water, shake to separate layers, wash the organic phase with water, dry the combined organic phase, and rotary evaporate to obtain product a2.

[0019] Furthermore, the ratio of product a1, ethyl acetate, epichlorohydrin, tetrabutylammonium bromide, and alkaline solution is 7-8g: 40-50mL: 10-11g: 0.7-0.9g: 13-15mL; the alkaline solution is a 40-45% potassium hydroxide solution.

[0020] In step A2, the amino group in product a1 undergoes ring opening and then ring closing with epichlorohydrin to generate an imidazole containing an epoxy group, which is product a2.

[0021] Step A3: Mix product a2, sodium aminonaphthalene sulfonate, and ethanol and stir for 20-30 min. Add triethylamine, heat to 85-95℃, stir for 2-2.5 h, cool the reaction solution to room temperature, add deionized water, stir for 30-35 min, place in an ice-water bath and let stand for 2 h, filter, wash, and vacuum dry to obtain product a3.

[0022] Furthermore, the ratio of product a2, sodium aminonaphthalenesulfonate, ethanol, and triethylamine is 18-20g: 25-27g: 105-115mL: 8-8.5g; the sodium aminonaphthalenesulfonate is 4-amino-1-naphthalenesulfonate sodium salt; and the volume fraction of ethanol is 95%.

[0023] In step A3, the epoxy group of product a2 reacts with an aromatic primary amino group containing sodium aminonaphthalenesulfonate to generate product a3 containing secondary alcohol, sodium naphthalenesulfonate, and imidazole.

[0024] Step A4: Mix terminal alkenyl carboxylic acid and acetonitrile and stir for 20-30 min. Place in an ice-water bath, add HOAt, and stir for 3-5 min. Add EDC and stir for 5-7 min. Add catalyst and product a3, heat to room temperature, and stir for 12-13 h. Add water and let stand for 5-10 min. Extract with ethyl acetate. Wash the organic phase once each with 5% citric acid aqueous solution, saturated sodium bicarbonate solution, and saturated brine. Dry and rotary evaporate to obtain product a4. In a protective gas atmosphere, mix product a4, haloalkoxysilane, and anhydrous ethanol, heat to 75-80℃, stir for 4-5 h, rotary evaporate, and dry to obtain monomer s.

[0025] Furthermore, the ratio of product a3, terminal alkenyl carboxylic acid, acetonitrile, HOAt, catalyst, and EDC is 21-22g: 10-11g: 105-115mL: 6.5-7.5g: 1-1.2g: 9-9.5g; the terminal alkenyl carboxylic acid is undecenoic acid; the catalyst is 4-dimethylaminopyridine; the ratio of product a4, haloalkoxysilane, and anhydrous ethanol is 32-34g: 12-14g: 90-100mL; the haloalkoxysilane is 3-chloropropyltrimethoxysilane.

[0026] In step A4, the terminal alkenyl carboxylic acid reacts with the secondary alcohol in product a3 to form an ester, yielding product a4 containing a terminal double bond; the tertiary amine in product a4 reacts with the halogen atom of a haloalkoxysilane to form a quaternary ammonium salt, yielding monomer s;

[0027] Step A5: Mix polyethylene glycol divinyl ether and deionized water for 30-35 minutes to obtain mixture 1; mix acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water for 20-25 minutes to obtain mixture 2; mix ascorbic acid, mercaptoacetic acid, and deionized water for 15-20 minutes to obtain mixture 3; mix mixture 1 and hydrogen peroxide solution for 5-7 minutes, and add mixture 2 and mixture 3 sequentially while stirring, completing the addition within 1.8-2 hours. Continue stirring for 2-2.5 hours. After cooling, adjust the pH to 6.8-7.2 to obtain a high-performance ultra-early strength polycarboxylate superplasticizer.

[0028] Further, in mixture 1, the ratio of polyethylene glycol divinyl ether to deionized water is 19-21g:115-125mL; in mixture 2, the ratio of acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, to deionized water is 32-34g:82-84g:5-7g:240-250mL; in mixture 3, the ratio of ascorbic acid, mercaptoacetic acid, to deionized water is 5.5-6g:1.6-1.8g:38-42mL; the ratio of mixture 1, hydrogen peroxide solution, mixture 2, to mixture 3 is 140-145mL:34-36mL:360-370mL:45-50mL; the mass fraction of hydrogen peroxide solution is 32-34%.

[0029] In step A5, polyethylene glycol divinyl ether, acrylic acid, monomer S, and 2-hydroxyethyl methacrylate phosphate undergo a polymerization reaction to obtain a high-performance ultra-early strength polycarboxylate superplasticizer.

[0030] This invention discloses a high-performance ultra-early strength polycarboxylate superplasticizer and its preparation method. First, monomer S is obtained by reacting nitroimidazole, epichlorohydrin, sodium aminonaphthalenesulfonate, terminal alkenyl carboxylic acid, and haloalkoxysilane as the main raw materials. Then, polyethylene glycol divinyl ether, acrylic acid, monomer S, and 2-hydroxyethyl methacrylate phosphate are polymerized to obtain the high-performance ultra-early strength polycarboxylate superplasticizer.

[0031] The beneficial effects of this invention are:

[0032] 1. This invention combines acrylic acid, monomer S, and 2-hydroxyethyl methacrylate phosphate. Sodium naphthalenesulfonate in monomer S adsorbs onto the surface of cement particles with quaternary ammonium salt and acrylic acid, forming a stable interface layer and improving overall dispersibility. The imidazole ring in monomer S reacts with Ca... 2+ The formation of weak coordination and local enrichment of calcium ions significantly lowers the CSH gel nucleation energy barrier, promoting early uniform CSH nucleation. The phosphate ester in 2-hydroxyethyl methacrylate reacts with Ca... 2+ Formation of strong complexes regulates the release rate of free calcium ions, while the imidazole ring traps Ca. 2+ The phosphate ester groups continuously replenish and maintain the local calcium ion concentration, prolonging the effective nucleation window period. The alkoxysilane in monomer S hydrolyzes into silanol in water, increasing the specific surface area of ​​nucleation sites and promoting CSH gel nucleation. The silanol forms a chemical bond with CSH, enhancing the interfacial bonding force between polycarboxylate superplasticizer and cement particles, and inhibiting microcrack propagation. They synergistically enhance the early strength improvement of cement-based concrete by polycarboxylate superplasticizer.

[0033] 2. The monomers s used in this invention contain nitroimidazole, epichlorohydrin, sodium aminonaphthalenesulfonate, terminal alkenyl carboxylic acid, and haloalkoxysilane. The products formed by the reaction have a large steric hindrance effect, which increases the insertion resistance of the polycarboxylate superplasticizer side chain to the interlayer of clay minerals (such as montmorillonite) carried in raw materials such as sand and stone. The silanols formed by the hydrolysis of alkoxysilanes form chemical bonds with the surface of cement particles, which greatly increases the adsorption of polycarboxylate superplasticizer in cement, thereby reducing its adsorption on clay minerals (such as montmorillonite) and giving polycarboxylate superplasticizer strong anti-mud properties. Detailed Implementation

[0034] 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, and 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.

[0035] Example 1

[0036] A high-performance, ultra-early-strength polycarboxylate superplasticizer is prepared by the following steps:

[0037] Step A1: Mix 1,2-dimethyl-5-nitroimidazole and an aqueous ethanol solution and stir for 25 min. Add sodium dithionite, heat to 50 °C, and stir for 3 h. Adjust the pH to 4.5 with 0.1 mol / L hydrochloric acid solution. Extract three times with 80 mL of ethyl acetate. Adjust the pH of the aqueous phase to 9 with 5% sodium bicarbonate solution. Extract four times with 60 mL of ethyl acetate. Collect the organic phase, wash it once with saturated sodium chloride solution, dry it with anhydrous sodium sulfate, filter, and rotary evaporate at 45 °C to obtain product a1. The ratio of 1,2-dimethyl-5-nitroimidazole, aqueous ethanol solution, and sodium dithionite is 7.5 g: 35 mL: 9.5 g. The aqueous ethanol solution is obtained by mixing ethanol and water in a 1:1 volume ratio and adjusting the pH to 8 with sodium bicarbonate. The volume fraction of ethanol is 95%.

[0038] Step A2: Mix product a1, ethyl acetate, and epichlorohydrin and stir for 10 min. Add tetrabutylammonium bromide, turn on reflux, heat to 90°C, stir for 3 h, cool to room temperature, add alkali solution, continue stirring for 2 h, add 70 mL of deionized water, shake to separate the layers, wash the organic phase three times with deionized water, dry the combined organic phase with anhydrous sodium sulfate, and rotary evaporate at 40°C to obtain product a2. The ratio of product a1, ethyl acetate, epichlorohydrin, tetrabutylammonium bromide, and alkali solution is 7 g: 40 mL: 10 g: 0.7 g: 13 mL; the alkali solution is a 40% potassium hydroxide solution.

[0039] Step A3: Mix product a2, sodium 4-amino-1-naphthalenesulfonate, and ethanol and stir for 20 min. Add triethylamine, heat to 85°C, and stir for 2 h. Cool the reaction solution to room temperature, add 300 mL of deionized water, stir for 30 min, and let stand in an ice-water bath for 2 h. Filter, wash three times with an ethanol-water mixture (ethanol to water volume ratio of 1:4), and vacuum dry at 40°C for 6 h to obtain product a3. The volume ratio of product a2, sodium 4-amino-1-naphthalenesulfonate, ethanol, and triethylamine is 18 g: 25 g: 105 mL: 8 g; the volume fraction of ethanol is 95%.

[0040] Step A4: Mix undecenoic acid and acetonitrile and stir for 20 min. Place in an ice-water bath, add HOAt, and stir for 3 min. Add EDC and stir for 5 min. Add 4-dimethylaminopyridine and product a3. Heat to room temperature and stir for 12 h. Add 1 mL of deionized water and let stand for 5 min. Extract with 310 mL of ethyl acetate. Wash the organic phase once each with 5% citric acid aqueous solution, saturated sodium bicarbonate solution, and saturated brine. Dry with anhydrous sodium sulfate and rotary evaporate at 30 °C. Product a4 was obtained; under nitrogen atmosphere, product a4, 3-chloropropyltrimethoxysilane, and anhydrous ethanol were mixed, heated to 75°C, stirred for 4 h, rotary evaporated at 40°C, and dried at 80°C for 4 h to obtain monomer s; the molar ratio of product a3, undecenoic acid, acetonitrile, HOAt, 4-dimethylaminopyridine, and EDC was 21 g: 10 g: 105 mL: 6.5 g: 1 g: 9 g; the molar ratio of product a4, 3-chloropropyltrimethoxysilane, and anhydrous ethanol was 32 g: 12 g: 90 mL;

[0041] Step A5: Mix polyethylene glycol divinyl ether (supplier: Hubei Xinhongli Chemical Co., Ltd., item number XHL4375) and deionized water for 30 min to obtain mixture 1; mix acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water for 20 min to obtain mixture 2; mix ascorbic acid, mercaptoacetic acid, and deionized water for 15 min to obtain mixture 3; mix mixture 1 and hydrogen peroxide solution for 5 min, then add mixture 2 and mixture 3 sequentially under stirring, completing the addition within 1.8 h, continue stirring for 2 h, cool to room temperature, and adjust the pH to 6.8 to obtain a high-performance ultra-early strength polycarboxylate superplasticizer;

[0042] In Mixture 1, the ratio of polyethylene glycol divinyl ether to deionized water is 19g:115mL; in Mixture 2, the ratio of acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water is 32g:82g:5g:240mL; in Mixture 3, the ratio of ascorbic acid, mercaptoacetic acid, and deionized water is 5.5g:1.6g:38mL; the ratio of Mixture 1, hydrogen peroxide solution, Mixture 2, and Mixture 3 is 140mL:34mL:360mL:45mL; the mass fraction of hydrogen peroxide solution is 32%; and the pH is adjusted using sodium hydroxide solution and hydrochloric acid solution, both with a concentration of 0.1mol / L.

[0043] Example 2

[0044] A high-performance, ultra-early-strength polycarboxylate superplasticizer is prepared by the following steps:

[0045] Step A1: Mix 1,2-dimethyl-5-nitroimidazole and an aqueous ethanol solution and stir for 27 min. Add sodium dithionite, heat to 55 °C, and stir for 3.5 h. Adjust the pH to 4.7 with 0.1 mol / L hydrochloric acid solution. Extract three times with 80 mL of ethyl acetate. Adjust the pH of the aqueous phase to 9.5 with 5% sodium bicarbonate solution and extract four times with 60 mL of ethyl acetate. Collect the organic phase, wash once with saturated sodium chloride solution, dry with anhydrous sodium sulfate, filter, and rotary evaporate at 45 °C to obtain product a1. The molar ratio of 1,2-dimethyl-5-nitroimidazole, aqueous ethanol solution, and sodium dithionite is 8.0 g: 40 mL: 10.0 g. The aqueous ethanol solution is obtained by mixing ethanol and water in a volume ratio of 1.5:1 and adjusting the pH to 8.5 with sodium bicarbonate. The volume fraction of ethanol is 95%.

[0046] Step A2: Mix product a1, ethyl acetate, and epichlorohydrin and stir for 15 min. Add tetrabutylammonium bromide, turn on reflux, heat to 95°C, stir for 3.5 h, cool to room temperature, add alkali solution, continue stirring for 2.3 h, add 77 mL of deionized water, shake to separate the layers, wash the organic phase three times with deionized water, dry the combined organic phase with anhydrous sodium sulfate, and rotary evaporate at 40°C to obtain product a2. The molar ratio of product a1, ethyl acetate, epichlorohydrin, tetrabutylammonium bromide, and alkali solution is 7.5 g: 45 mL: 10.5 g: 0.8 g: 14 mL; the alkali solution is a 43% potassium hydroxide solution.

[0047] Step A3: Mix product a2, sodium 4-amino-1-naphthalenesulfonate, and ethanol and stir for 25 min. Add triethylamine, heat to 90℃, and stir for 2.3 h. Cool the reaction solution to room temperature, add 315 mL of deionized water, stir for 33 min, and let stand in an ice-water bath for 2 h. Filter, wash three times with an ethanol-water mixture (ethanol to water volume ratio of 1:4), and vacuum dry at 40℃ for 6 h to obtain product a3. The volume ratio of product a2, sodium 4-amino-1-naphthalenesulfonate, ethanol, and triethylamine is 19 g: 26 g: 110 mL: 8.3 g; the volume fraction of ethanol is 95%.

[0048] Step A4: Undecenoic acid and acetonitrile were mixed and stirred for 25 min, placed in an ice-water bath, HOAt was added, and stirred for 4 min. EDC was added, and stirred for 6 min. 4-Dimethylaminopyridine and product a3 were added, the mixture was heated to room temperature, stirred for 12.5 h, 1.5 mL of deionized water was added, and the mixture was allowed to stand for 7 min. It was extracted with 325 mL of ethyl acetate. The organic phase was washed once each with 5% citric acid aqueous solution, saturated sodium bicarbonate solution, and saturated brine. It was dried with anhydrous sodium sulfate and rotary evaporated at 30 °C to obtain product a4. Under nitrogen atmosphere, product a4, 3-chloropropyltrimethoxysilane, and anhydrous ethanol were mixed, heated to 78 °C, stirred for 4.5 h, rotary evaporated at 40 °C, and dried at 80 °C for 4 h to obtain monomer s.

[0049] The ratio of product a3, undecenoic acid, acetonitrile, HOAt, 4-dimethylaminopyridine, and EDC was 21.5g:10.5g:110mL:7.0g:1.1g:9.3g; the ratio of product a4, 3-chloropropyltrimethoxysilane, and anhydrous ethanol was 33g:13g:95mL.

[0050] Step A5: Mix polyethylene glycol divinyl ether (supplier: Hubei Xinhongli Chemical Co., Ltd., item number XHL4375) and deionized water for 33 min to obtain mixture 1; mix acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water for 23 min to obtain mixture 2; mix ascorbic acid, mercaptoacetic acid, and deionized water for 18 min to obtain mixture 3; mix mixture 1 and hydrogen peroxide solution for 6 min, and add mixture 2 and mixture 3 sequentially under stirring, completing the addition within 1.9 h, continue stirring for 2.3 h, cool to room temperature, and adjust the pH to 7.0 to obtain a high-performance ultra-early strength polycarboxylate superplasticizer;

[0051] In Mixture 1, the ratio of polyethylene glycol divinyl ether to deionized water is 20g:120mL; in Mixture 2, the ratio of acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water is 33:83g:6g:245mL; in Mixture 3, the ratio of ascorbic acid, mercaptoacetic acid, and deionized water is 5.8g:1.7g:40mL; the ratio of Mixture 1, hydrogen peroxide solution, Mixture 2, and Mixture 3 is 143mL:35mL:365mL:47mL; the mass fraction of hydrogen peroxide solution is 33%; and the pH is adjusted using sodium hydroxide solution and hydrochloric acid solution, both with a concentration of 0.1mol / L.

[0052] Example 3

[0053] A high-performance, ultra-early-strength polycarboxylate superplasticizer is prepared by the following steps:

[0054] Step A1: Mix 1,2-dimethyl-5-nitroimidazole and an aqueous ethanol solution and stir for 30 min. Add sodium dithionite, heat to 60 °C, and stir for 4 h. Adjust the pH to 5 with 0.1 mol / L hydrochloric acid solution, extract three times with 80 mL of ethyl acetate, adjust the pH of the aqueous phase to 10 with 5% sodium bicarbonate solution, extract four times with 60 mL of ethyl acetate, collect the organic phase, wash once with saturated sodium chloride solution, dry with anhydrous sodium sulfate, filter, and rotary evaporate at 45 °C to obtain product a1; the molar ratio of 1,2-dimethyl-5-nitroimidazole, aqueous ethanol solution, and sodium dithionite is 8.5 g: 45 mL: 10.5 g; the aqueous ethanol solution is obtained by mixing ethanol and water in a volume ratio of 2:1, and adjusting the pH to 9 with sodium bicarbonate; the volume fraction of ethanol is 95%.

[0055] Step A2: Mix product a1, ethyl acetate, and epichlorohydrin and stir for 20 min. Add tetrabutylammonium bromide, turn on reflux, heat to 100℃, stir for 4 h, cool to room temperature, add alkali solution, continue stirring for 2.5 h, add 85 mL of deionized water, shake to separate the layers, wash the organic phase three times with deionized water, dry the combined organic phase with anhydrous sodium sulfate, and rotary evaporate at 40℃ to obtain product a2. The molar ratio of product a1, ethyl acetate, epichlorohydrin, tetrabutylammonium bromide, and alkali solution is 8 g: 50 mL: 11 g: 0.9 g: 15 mL; the alkali solution is a 45% potassium hydroxide solution.

[0056] Step A3: Mix product a2, sodium 4-amino-1-naphthalenesulfonate, and ethanol and stir for 30 min. Add triethylamine, heat to 95℃, and stir for 2.5 h. Cool the reaction solution to room temperature, add 350 mL of deionized water, stir for 35 min, and let stand in an ice-water bath for 2 h. Filter, wash three times with an ethanol-water mixture (ethanol to water volume ratio of 1:4), and vacuum dry at 40℃ for 6 h to obtain product a3. The volume ratio of product a2, sodium 4-amino-1-naphthalenesulfonate, ethanol, and triethylamine is 20 g: 27 g: 115 mL: 8.5 g; the volume fraction of ethanol is 95%.

[0057] Step A4: Undecenoic acid and acetonitrile were mixed and stirred for 30 min, placed in an ice-water bath, HOAt was added, and stirred for 5 min. EDC was added, and stirred for 7 min. 4-Dimethylaminopyridine and product a3 were added, the mixture was heated to room temperature, stirred for 13 h, 2 mL of deionized water was added, and the mixture was allowed to stand for 10 min. It was extracted with 330 mL of ethyl acetate. The organic phase was washed once each with 5% citric acid aqueous solution, saturated sodium bicarbonate solution, and saturated saline solution. It was dried with anhydrous sodium sulfate and rotary evaporated at 30 °C to obtain product a4. Under nitrogen atmosphere, product a4, 3-chloropropyltrimethoxysilane, and anhydrous ethanol were mixed, heated to 80 °C, stirred for 5 h, rotary evaporated at 40 °C, and dried at 80 °C for 4 h to obtain monomer s.

[0058] The ratio of product a3, undecenoic acid, acetonitrile, HOAt, 4-dimethylaminopyridine, and EDC is 22g:11g:115mL:7.5g:1.2g:9.5g; the ratio of product a4, 3-chloropropyltrimethoxysilane, and anhydrous ethanol is 34g:14g:100mL.

[0059] Step A5: Mix polyethylene glycol divinyl ether (supplier: Hubei Xinhongli Chemical Co., Ltd., item number XHL4375) and deionized water for 35 min to obtain mixture 1; mix acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water for 25 min to obtain mixture 2; mix ascorbic acid, mercaptoacetic acid, and deionized water for 20 min to obtain mixture 3; mix mixture 1 and hydrogen peroxide solution for 7 min, then add mixture 2 and mixture 3 sequentially under stirring, completing the addition within 2 h, continue stirring for 2.5 h, cool to room temperature, and adjust the pH to 7.2 to obtain a high-performance ultra-early strength polycarboxylate superplasticizer;

[0060] In Mixture 1, the ratio of polyethylene glycol divinyl ether to deionized water is 21g:125mL; in Mixture 2, the ratio of acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water is 34g:84g:7g:250mL; in Mixture 3, the ratio of ascorbic acid, mercaptoacetic acid, and deionized water is 6g:1.8g:42mL; the ratio of Mixture 1, hydrogen peroxide solution, Mixture 2, and Mixture 3 is 145mL:36mL:370mL:50mL; the mass fraction of hydrogen peroxide solution is 34%; and the pH is adjusted using sodium hydroxide solution and hydrochloric acid solution, both with a concentration of 0.1mol / L.

[0061] Comparative Example 1

[0062] Compared with Example 3, product a3 was replaced with product a3-1, and everything else was exactly the same as in Example 3, to obtain a high-performance ultra-early strength polycarboxylate superplasticizer;

[0063] Specifically:

[0064] Sodium 4-amino-1-naphthalenesulfonate, ethyl acetate, and epichlorohydrin were mixed and stirred for 20 min. Tetrabutylammonium bromide was added, and the mixture was refluxed, heated to 100 °C, and stirred for 4 h. After cooling to room temperature, alkali solution was added, and stirring was continued for 2.5 h. 85 mL of deionized water was added, and the mixture was shaken to separate the layers. The organic phase was washed three times with water, and the combined organic phase was dried with anhydrous sodium sulfate and rotary evaporated at 40 °C to obtain product a2-1. The ratio of sodium 4-amino-1-naphthalenesulfonate, ethyl acetate, epichlorohydrin, tetrabutylammonium bromide, and alkali solution was 8 g: 50 mL: 11 g: 0.9 g: 15 mL. The alkali solution was a 45% potassium hydroxide solution.

[0065] Product a2-1, product a1, and ethanol were mixed and stirred for 30 min. Triethylamine was added, and the mixture was heated to 95 °C and stirred for 2.5 h. The reaction solution was cooled to room temperature, and 350 mL of deionized water was added. The mixture was stirred for 35 min and placed in an ice-water bath for 2 h. The mixture was then filtered and washed three times with an ethanol-water mixture (ethanol to water volume ratio of 1:4). The mixture was then vacuum dried at 40 °C for 6 h to obtain product a3-1. The volume ratio of product a2-1, product a1, ethanol, and triethylamine was 20 g: 27 g: 115 mL: 8.5 g. The volume fraction of ethanol was 95%.

[0066] Comparative Example 2

[0067] Compared with Example 3, the monomer s used was replaced with monomer s-1, and the rest was exactly the same as in Example 3, to obtain a high-performance ultra-early strength polycarboxylate superplasticizer;

[0068] Specifically:

[0069] In nitrogen atmosphere, product a3, 3-chloropropyltrimethoxysilane, and anhydrous ethanol were mixed, heated to 80°C, stirred for 5 h, rotary evaporated at 40°C, and dried at 80°C for 4 h to obtain product 1; the ratio of product a3, 3-chloropropyltrimethoxysilane, and anhydrous ethanol was 34 g: 14 g: 100 mL.

[0070] Undecenoic acid and acetonitrile were mixed and stirred for 30 min, placed in an ice-water bath, HOAt was added, and stirred for 5 min. EDC was added, and stirred for 7 min. 4-Dimethylaminopyridine and product 1 were added, the mixture was heated to room temperature, stirred for 13 h, 2 mL of water was added, and the mixture was allowed to stand for 10 min. It was then extracted with 330 mL of ethyl acetate. The organic phase was washed once each with 5% citric acid aqueous solution, saturated sodium bicarbonate solution, and saturated saline solution. It was dried with anhydrous sodium sulfate and rotary evaporated at 30 °C to obtain monomer s-1. The molar ratio of product 1, undecenoic acid, acetonitrile, HOAt, 4-dimethylaminopyridine, and EDC was 22 g: 11 g: 115 mL: 7.5 g: 1.2 g: 9.5 g.

[0071] Comparative Example 3

[0072] Compared with Example 3, the 3-chloropropyltrimethoxysilane used was replaced with 3-chloro-1-propanol, and the rest was exactly the same as in Example 3, to obtain a high-performance ultra-early strength polycarboxylate superplasticizer.

[0073] The effects of the polycarboxylate superplasticizers prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention were further tested below, and the test results are shown below.

[0074] Portland cement (strength 42.5), fly ash (Grade II), mineral powder (S95), river sand (Class I), crushed stone (Class I), water, and the polycarboxylate superplasticizer prepared in Examples 1-3 and Comparative Examples 1-3 were mixed in a mix proportion of 210:15:65:810:1090:170:8.0 to prepare fresh concrete. Performance tests were conducted on the fresh concrete; the water reduction rate was tested according to GB / T 8076-2008; and the compressive strength after curing at 5℃ and 25℃ for 1 day was tested according to GB / T 50081-2019.

[0075] The results are recorded in Table 1;

[0076] Table 1: Test Results

[0077]

[0078] According to the data in Table 1, the polycarboxylate superplasticizer prepared by this invention has good anti-mud properties and early strength properties, and enables the prepared concrete to have a high water reduction rate and 1-day compressive strength.

[0079] Comparing Example 3 with Comparative Example 1, it can be seen that replacing product a3 with product a3-1 demonstrates that the polycarboxylate superplasticizer prepared using product a3 in this invention can impart higher water reduction rate and 1-day compressive strength to concrete.

[0080] Comparing Example 3 with Comparative Example 2, it can be seen that replacing monomer s with monomer s-1 demonstrates that the polycarboxylate superplasticizer prepared using monomer s in this invention can impart a higher water reduction rate and 1-day compressive strength to concrete.

[0081] A comparison of Example 3 and Comparative Example 3 shows that replacing the 3-chloropropyltrimethoxysilane used with 3-chloro-1-propanol demonstrates that the polycarboxylate superplasticizer prepared using 3-chloropropyltrimethoxysilane in this invention can impart higher 1-day compressive strength to concrete.

[0082] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-performance, ultra-early-strength polycarboxylate superplasticizer, characterized in that: Includes the following steps: Step A1: Mix and stir the nitroimidazole-containing aqueous ethanol solution, add the reducing agent, heat and stir to obtain product a1; Step A2: After mixing and stirring product a1, ethyl acetate and epichlorohydrin, tetrabutylammonium bromide is added, reflux is turned on, and the mixture is heated and stirred. After cooling to room temperature, alkali solution is added, and stirring is continued to obtain product a2. Step A3: Mix product a2, sodium aminonaphthalene sulfonate, and ethanol, stir, add triethylamine, heat and stir to obtain product a3; Step A4: Mix and stir the terminal alkenyl carboxylic acid and acetonitrile, place in an ice-water bath, add HOAt, stir, add EDC, continue stirring, add catalyst and product a3, heat to room temperature, and stir to obtain product a4; under a protective gas, mix product a4, haloalkoxysilane and anhydrous ethanol, heat and stir to obtain monomer s; Step A5: Mix polyethylene glycol divinyl ether and deionized water to obtain mixture 1; mix acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water to obtain mixture 2; mix ascorbic acid, mercaptoacetic acid, and deionized water to obtain mixture 3; mix mixture 1 and hydrogen peroxide solution, then add mixture 2 and mixture 3 sequentially while stirring, continue stirring, cool, and adjust the pH to obtain a high-performance ultra-early strength polycarboxylate superplasticizer.

2. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A1, the ratio of the amount of nitroimidazole, ethanol aqueous solution, and reducing agent is 7.5-8.5g: 35-45mL: 9.5-10.5g; the nitroimidazole is 1,2-dimethyl-5-nitroimidazole.

3. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A1, the ethanol-water solution is obtained by mixing ethanol and water in a volume ratio of 1-2:1, and adding sodium bicarbonate to adjust the pH to 8-9.

4. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A2, the ratio of product a1, ethyl acetate, epichlorohydrin, tetrabutylammonium bromide, and alkaline solution is 7-8g: 40-50mL: 10-11g: 0.7-0.9g: 13-15mL.

5. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A3, the ratio of product a2, sodium aminonaphthalenesulfonate, ethanol, and triethylamine is 18-20g: 25-27g: 105-115mL: 8-8.5g; the sodium aminonaphthalenesulfonate is 4-amino-1-naphthalenesulfonate sodium salt.

6. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A4, the ratio of product a3, terminal alkenyl carboxylic acid, acetonitrile, HOAt, catalyst, and EDC is 21-22g: 10-11g: 105-115mL: 6.5-7.5g: 1-1.2g: 9-9.5g.

7. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A4, the ratio of product a4, haloalkoxysilane, and anhydrous ethanol is 32-34g: 12-14g: 90-100mL.

8. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A5, the ratio of polyethylene glycol divinyl ether to deionized water in mixture 1 is 19-21g: 115-125mL; the ratio of acrylic acid, monomer S, 2-hydroxyethyl methacrylate phosphate, and deionized water in mixture 2 is 32-34g: 82-84g: 5-7g: 240-250mL.

9. The preparation method of a high-performance ultra-early strength polycarboxylate superplasticizer according to claim 1, characterized in that: In step A5, the ratio of ascorbic acid, thioglycolic acid, and deionized water in mixture 3 is 5.5-6g. 1.6-1.8g: 38-42mL; The ratio of the amount of mixture 1, hydrogen peroxide solution, mixture 2, and mixture 3 is 140-145mL: 34-36mL: 360-370mL: 45-50mL.

10. A high-performance ultra-early strength polycarboxylate superplasticizer, prepared by the preparation method of the high-performance ultra-early strength polycarboxylate superplasticizer according to any one of claims 1-9.

Images