Low-sensitivity viscosity reduction type polycarboxylate superplasticizer as well as preparation method and application thereof

Abstract

The invention discloses a low-sensitivity viscosity reduction type polycarboxylic acid water reducer and a preparation method and application thereof, and belongs to the technical field of concrete admixtures, the polycarboxylic acid water reducer is prepared by free radical copolymerization reaction of unsaturated acid monomer, unsaturated sulfonate monomer, unsaturated phosphating polyoxyethylene ether monomer and functional monomer according to the molar ratio of a: b: c: d = (3-6): (0.5-2): 1: (0.06-1.2), the molecular weight and the polymerization degree of a main chain can be controlled by designing the molecular structure of the water reducing agent, so that the density of side chains is changed, different steric hindrance effects are generated, functional group monomers with different surface activities are selectively introduced for polymerization reaction, the hydrophilic-lipophilic balance value of the water reducing agent is changed, and the water reducing effect is improved. The adsorption capacity, the dispersing performance and the viscosity reduction performance of the water reducer can be subjected to gradient efficiency design, functionalization of the polycarboxylic acid water reducer is achieved, and the comprehensive application effect of the polycarboxylic acid water reducer in concrete is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete admixtures, and particularly relates to a low-sensitivity viscosity-reducing polycarboxylate water reducer, a preparation method thereof and an application thereof. Background Art

[0002] As the third-generation high-performance water reducer, the polycarboxylate water reducer has a comb-shaped molecular structure. Through the electrostatic repulsion provided by groups such as carboxyl and sulfonic acid groups on the main chain structure and the steric hindrance effect provided by the grafted side chains, the free water in the cement particle flocculation structure is released, so as to achieve the effect of dispersion and water reduction. In recent years, under the background of the great wave of infrastructure construction in China, the polycarboxylate water reducer has become the most widely used water reducer in the engineering construction field due to a series of advantages such as low dosage, excellent dispersion performance, functional designability and environmental friendliness.

[0003] With the large-scale use of concrete causing huge consumption of natural resources and the near exhaustion of high-quality sand and stone resources, it has become an inevitable trend to apply low-quality aggregates such as recycled aggregates, industrial waste residues and manufactured sand to concrete. During the construction process, a small change in the dosage of the polycarboxylate water reducer at the reasonable dosage point will lead to insufficient fluidity or too fast loss of fresh concrete, or lead to sensitivity problems such as segregation and bleeding of concrete, making the control of concrete production more difficult, thus bringing great risks to the quality control of concrete.

[0004] At present, the main method to improve the strength of concrete is to achieve it by reducing the water-binder ratio. However, increasing the strength of concrete by reducing the water-binder ratio will increase the viscosity of concrete, resulting in difficulties in the initial slow dispersion and stable control of fluidity of high-strength concrete, and problems such as high pump pressure and pipe blockage during the construction process, which will easily cause quality problems when using high-grade concrete, restricting the development of high-strength concrete.

[0005] In view of the above problems, some scholars have utilized the designability of polycarboxylate superplasticizer molecules to prepare low-sensitivity or viscosity-reducing polycarboxylate superplasticizers by grafting molecular groups with slump retention and viscosity reduction functions, so as to solve problems such as difficult concrete construction at the present stage. Chinese Patent Document CN114195953B discloses "a low-sensitivity and high-water-retention polycarboxylate superplasticizer and its preparation method". By introducing caffeic acid γ-cyclodextrin unsaturated monomer and crosslinking agent trimethylolpropane triacrylate into the polycarboxylate superplasticizer, the release of free water is effectively reduced, and the prepared superplasticizer has excellent water retention and low sensitivity. However, this method has a long reaction time and a complex control process, and undoubtedly reduces the dispersing ability of the superplasticizer. Chinese Patent Document CN116478343B discloses "a viscosity-reducing polycarboxylate superplasticizer and its preparation method". First, an unsaturated phosphorus-nitrogen derivative is prepared from a phosphoryl chloride derivative and an unsaturated amine, and the polycarboxylate superplasticizer prepared by copolymerizing it with methoxypolyethylene glycol acrylate, unsaturated carboxylic acid, and unsaturated carboxylic acid ester contains a strongly polar phosphoramide group that is not easily hydrolyzed. This superplasticizer has a low dosage, a high water reduction rate, good dispersibility for cement, low bleeding rate of the concrete prepared by it, good dispersion retention ability, and strong operability. However, this method has harsh reaction conditions, some reactions need to be carried out at low temperature, it is not easy to scale up production, the reaction solvent involves organic solvents, and harmful substances such as inhibitors are involved, resulting in great environmental protection pressure during the production process. To sum up, the existing polycarboxylate superplasticizers do not have comprehensive properties such as high dispersion, low sensitivity, and viscosity reduction. Moreover, most of the preparation processes of polycarboxylate superplasticizers are harsh and complex, with a long reaction time, and the solvents used have certain hazards. Summary of the Invention

[0006] Technical problems to be solved: In view of the problems existing in the application of polycarboxylate superplasticizers in the background technology, the present invention provides a low-sensitivity and viscosity-reducing polycarboxylate superplasticizer, its preparation method and application. While having a water reduction rate superior to that of conventional products, this polycarboxylate superplasticizer has the advantages of low sensitivity and viscosity reduction, effectively solving problems such as poor fluidity, high viscosity, and poor robustness caused by the reduction of the water-binder ratio in high-strength concrete, meeting the application adaptability of various admixtures and different-quality manufactured sand, increasing the dispersion effect, providing better construction performance, and having a wide application prospect.

[0007] Technical solution: A low-sensitivity and viscosity-reducing polycarboxylate superplasticizer described in the present invention, the structural formula of the polycarboxylate superplasticizer is shown in Formula I: Formula I; In Formula I: R 1 is -H or -COOH, R 2 is -H, -CH 3 or -CH 2 COOH, R 3 is -H or -CH3 , M 1 is Na, R 4 is H or CH 3 , R 5 is -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 - or -OCH 2 CH 2 , R 6 is -H or CH 3 , R 7 is C 1 or C 3 of the alkyl group, R 8 , R 9 , R 10 is -CH 3 , -CH 3 O, -CH 2 CH 3 O; a, b, c, d represent the molar amounts of each repeating unit; the molecular weight of the polycarboxylate water reducer is 20,000 - 60,000 Da.

[0008] Preferably, the polycarboxylate water reducer is prepared by free radical copolymerization of an unsaturated acid monomer, an unsaturated sulfonate monomer, an unsaturated phosphated polyoxyethylene ether monomer and a functional monomer in a molar ratio of a:b:c:d = (3 - 6):(0.5 - 2):1:(0.06 - 1.2).

[0009] Preferably, the structural formula of the unsaturated acid monomer is as shown in Formula II: Formula II; In Formula II: R 1 is -H or -COOH, R 2 is -H, -CH 3 or -CH 2 COOH; wherein, if R 1 is -COOH, R 2 is -H; if R 2 is -CH 2 COOH, R 1 is -H; The unsaturated acid monomer is one or more of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid in any proportion combination.

[0010] Preferably, the structural formula of the unsaturated sulfonic acid or its salt monomer is as shown in Formula III: Formula III; In Formula III: R 3 is -H or -CH 3 , M 1 is Na; The unsaturated sulfonate monomer is one or two of sodium allylsulfonate and sodium methallylsulfonate in any proportion combination.

[0011] Preferably, the unsaturated phosphorylated polyoxyethylene ether monomer is a macromonomer with a polyether long-chain structure and continues to be phosphorylated after being glucosidated at the end, and its end group contains an unsaturated carbon-carbon double bond. Its structural formula is shown in Formula IV: Formula IV; In Formula IV: R 4 is -H or -CH 3 , R 5 is -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 - or -OCH 2 CH 2 -, n is the number of structural units, n = 38 - 152; the molecular weight of the unsaturated phosphorylated polyoxyethylene ether monomer is 2000 - 7000.

[0012] Preferably, the structural formula of the functional monomer is shown in Formula V: Formula V; In Formula V: R 6 is -H or an alkyl group of C 1 ~C 3 , R 7 is an alkyl group of C 1 or C 3 , R 8 , R 9 , R 10 is -CH 3 , -CH 3 O, -CH 2 CH 3 O; any one of them; The functional monomer is one or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, methacryloyloxypropyltriethoxysilane, methacryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, (3-acryloyloxy)dimethylmethoxysilane, methacryloyloxymethyltriethoxysilane, methacryloyloxypropyltriethoxysilane.

[0013] The present invention discloses a preparation method of a low-sensitivity viscosity-reducing polycarboxylate water reducer. The preparation method includes the following steps: Step 1: Prepare an unsaturated phosphated polyoxyethylene ether monomer: Add the unsaturated polyoxyethylene ether monomer and glucose into a reaction vessel and mix evenly. Add an inhibitor, heat up to 60-80 °C, then add a catalyst and heat up to 95-110 °C under a vacuum state, keep warm for 3-8 h and then cool to 25-30 °C, adjust the pH value to 7-8 to obtain a terminal glucosidated unsaturated polyoxyethylene ether monomer; then, under a protective atmosphere, heat up to 50-70 °C, and add polyphosphoric acid or P 2 O 5 in batches into the reaction vessel, stir and mix evenly, heat up to 80-100 °C, carry out a phosphating reaction for 4-8 h, and obtain an unsaturated phosphated polyoxyethylene ether monomer after cooling; Step 2: Add an oxidant, a catalyst, a functional monomer and water to the prepared unsaturated phosphated polyoxyethylene ether monomer, mix evenly to form a base solution, heat up to 25-55 °C, and stir and mix evenly for 5-10 min; Mix the unsaturated acid monomer, a reducing agent, a chain transfer agent and water evenly to prepare a dropping solution A; Mix the unsaturated sulfonic acid or its salt monomer and water evenly to prepare a dropping solution B; Gradually drop the dropping solution A and the dropping solution B into the base solution simultaneously through a peristaltic pump for reaction, the dropping time is 0.5-2 h, and the dropping temperature is controlled at 25-55 °C; wherein, the solid content of the base solution and the dropping solution is 15-60%; then keep warm and react for 1-2 h, and then add an alkaline neutralizing agent to adjust the pH value of the reaction solution to 6-8 to obtain the polycarboxylate water reducer.

[0014] Preferably, in step 1, the molar ratio of the unsaturated polyoxyethylene ether monomer, glucose, and polyphosphoric acid is 1:(1-1.1):(1-1.2), or the molar ratio of the unsaturated polyoxyethylene ether monomer, glucose, and P 2 O 5 is 1:(1-1.1):(0.5-0.6); The inhibitor is hydroquinone, and the dosage of hydroquinone is 0.001-0.004% of the weight of the unsaturated polyoxyethylene ether monomer; The catalyst is benzenesulfonic acid or p-toluenesulfonic acid, and the dosage of the catalyst is 0.15-0.4% of the weight of glucose; The degree of vacuum of the vacuum state is -0.080 to -0.096 MPa; The lye for adjusting pH is a sodium hydroxide solution with a mass fraction of 30%; The polyphosphoric acid is one or more of tripolyphosphoric acid, tetrapolyphosphoric acid, pentapolyphosphoric acid, and hexapolyphosphoric acid. In terms of the mass fraction of phosphoric acid, its industrial-grade content is 105 to 118%; The unsaturated polyoxyethylene ether monomer is one or more of methyl allyl polyoxyethylene ether with a molecular weight of 2000 to 4000, isopentenol polyoxyethylene ether with a molecular weight of 3000 to 4000, 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 3000 to 5000, and ethylene glycol mono vinyl polyethylene glycol ether with a molecular weight of 3000 to 6000.

[0015] Preferably, in step 2, the oxidant is one or more of hydrogen peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate, and its dosage is 1 to 4% of the total molar amount of all unsaturated polymerization monomers; The reducing agent is one or more of L-ascorbic acid, sodium hypophosphite, sodium bisulfite, and sodium metabisulfite, and its dosage is 0.2 to 1% of the total molar amount of unsaturated polymerization monomers; The chain transfer agent is one or more of mercaptoethanol, mercaptoacetic acid, and mercaptopropionic acid, and its dosage is 1.6 to 4.8% of the total molar amount of unsaturated polymerization monomers; The catalyst used in the polymerization reaction is one of ferrous sulfate, ferrous chloride, and copper chloride, and its dosage is 0.006 to 0.01% of the total molar amount of unsaturated polymerization monomers; The alkaline neutralizer is a sodium hydroxide solution with a mass fraction of 30%.

[0016] The present invention also discloses an application of a low-sensitivity viscosity-reducing polycarboxylate water reducer in a gel material. The dosage of the polycarboxylate water reducer is 0.05 to 0.5% by mass of the total cementitious material, and its dosage is the dosage of pure solid.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The polycarboxylate water reducer of the present invention has the advantages of low sensitivity and viscosity reduction while having a leading water reduction rate compared with conventional products. It effectively solves the problems of poor fluidity, high viscosity, and poor robustness caused by a low water-binder ratio in high-strength concrete, meets the application adaptability of various admixtures and different qualities of manufactured sand, increases the dispersion effect, provides better construction performance, and has a wide application prospect; 2. After phosphorylating the end of the unsaturated polyoxyethylene ether monomer in this polycarboxylate superplasticizer, the phosphate group has stronger electronegativity and chelating ability, and has a higher affinity on the surface of cement and different types of inert powder particles, and can quickly reach a relatively high adsorption amount. At the same time, the phosphate group can form a stable complex with Ca in the cement, delaying the hydration process of the cement, effectively improving the fluidity and slump retention performance of the concrete, and significantly enhancing the dispersion performance and viscosity reduction performance of the polycarboxylate superplasticizer. 2+ This forms a stable complex, delays the hydration process of the cement, effectively improves the fluidity and slump retention performance of the concrete, and significantly enhances the dispersion performance and viscosity reduction performance of the polycarboxylate superplasticizer. 3. This polycarboxylate superplasticizer introduces sulfonic acid groups and siloxane groups. The released sulfonate ions endow the polycarboxylate superplasticizer with more adsorption selectivity. The sulfonate ions compete with the polycarboxylate superplasticizer for adsorption on the clay surface, thereby reducing the adsorption of the clay on the polycarboxylate superplasticizer and achieving a better water reduction and setting retardation and slump retention effect. Introducing siloxane groups can adjust the ratio of hydrophilic groups and hydrophobic groups, optimize the bubble structure of the concrete system, and significantly improve the homogeneity of the concrete. In addition, the siloxane groups significantly enhance the anchoring ability of the superplasticizer on the surface of cement and mineral admixture particles, effectively enhancing the slump retention effect and significantly improving the comprehensive performance of the concrete. 4. This polycarboxylate superplasticizer modifies with glucosylated ends to increase the steric hindrance effect of the polyether side chain, hinders the intercalation adsorption of the clay on the polyether side chain, reduces the sensitivity of the superplasticizer to the clay, and improves the material adaptability. At the same time, the introduced glucose molecules have a good setting retardation effect, which is beneficial to maintaining the workability of the concrete at high temperatures and for a long time, and improving the weather resistance adaptability of the superplasticizer. 5. In the synthesis of this polycarboxylate superplasticizer, the molecular weight and the degree of polymerization of the main chain can be controlled by designing the molecular structure of the superplasticizer, thereby changing the side chain density and generating different steric hindrance effects. Selecting and introducing functional group monomers with different surface activities for polymerization reactions to change the hydrophilic-lipophilic balance value (HLB) of the superplasticizer enables the adsorption ability, dispersion performance, and viscosity reduction performance of the superplasticizer to be designed with gradient efficacy, ultimately realizing the functionalization of the polycarboxylate superplasticizer, and the comprehensive application effect in concrete will also be significantly improved. 6. This polycarboxylate superplasticizer has the advantages of high water reduction, long slump retention, low sensitivity, and reducing the viscosity of the concrete. It can effectively solve the problems of fluctuations in fluidity and state caused by unstable quality of concrete materials, and application problems such as unfavorable construction due to high viscosity of high-strength concrete. The unsaturated polyoxyethylene ether required in the synthesis includes common polyether types and has wide adaptability. 7. The preparation method of the present invention has the advantages of simple preparation process, greatly shortened reaction time, high production efficiency, environmental friendliness, etc., and has great significance for promoting the research of polycarboxylate superplasticizers and improving the application technology level of concrete.

[0018] Other beneficial effects of the present invention are described in the embodiment part of the specification and will not be elaborated here. Brief Description of the Drawings

[0019] Figure 1 It is a flow chart of the preparation method of the low-sensitivity viscosity-reducing polycarboxylate water reducer of the present invention. Detailed Embodiments

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will combine the attached Figure 1 The technical solutions of the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0021] The present invention discloses a low-sensitivity viscosity-reducing polycarboxylate water reducer, and the structural formula of the polycarboxylate water reducer is shown in Formula I: Formula I; In Formula I: R 1 is -H or -COOH, R 2 is -H, -CH 3 or -CH 2 COOH, R 3 is -H or -CH 3 , M 1 is Na, R 4 is H or CH 3 , R 5 is -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 -, or -OCH 2 CH 2 , R 6 is -H or CH 3 , R 7 is C 1 or C 3 alkyl, R 8 , R 9 , R 10 is -CH 3 , -CH 3 O, -CH 2 CH 3Any one of O; a, b, c, d, and n represent the molar amounts of each repeating unit; the molecular weight of the polycarboxylate water reducer is 20,000 to 60,000 Da. The polycarboxylate water reducer is prepared by free radical copolymerization of an unsaturated acid monomer, an unsaturated sulfonate monomer, an unsaturated phosphorylated polyoxyethylene ether monomer, and a functional monomer according to a molar ratio of a:b:c:d = (3 to 6):(0.5 to 2):1:(0.06 to 1.2). The polycarboxylate water reducer of the present invention has the advantages of a leading water reduction rate compared to conventional products, low sensitivity, and viscosity reduction. It effectively solves the problems of poor fluidity, high viscosity, and poor robustness caused by a low water-binder ratio in high-strength concrete, meets the application adaptability of various admixtures and different qualities of manufactured sand, increases the dispersion effect, provides better construction performance, and has broad application prospects.

[0022] Among them, the structural formula of the unsaturated acid monomer is shown in Formula II: Formula II; In Formula II: R 1 is -H or -COOH, and R 2 is -H, -CH 3 or -CH 2 COOH; among them, if R 1 is -COOH, then R 2 is -H; if R 2 is -CH 2 COOH, then R 1 is -H; the unsaturated acid monomer is one or more of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid in any proportion combination.

[0023] Among them, the structural formula of the unsaturated sulfonic acid or its salt monomer is shown in Formula III: Formula III; In Formula III: R 3 is -H or -CH 3 , and M 1 is Na; the unsaturated sulfonate monomer is one or two of sodium allyl sulfonate, sodium methallyl sulfonate in any proportion combination. The introduction of the sulfonic acid group in this polycarboxylate water reducer makes the released sulfonate ions endow the polycarboxylate water reducer with more adsorption selectivity. The sulfonate ions compete with the polycarboxylate water reducer for adsorption on the clay surface, thereby reducing the adsorption of the clay on the polycarboxylate water reducer and achieving a better water reduction and setting retardation and slump retention effect; Among them, the unsaturated phosphorylated polyoxyethylene ether monomer is a macromonomer with a polyether long-chain structure and terminal glucosidation followed by phosphorylation, and its end group contains an unsaturated carbon-carbon double bond, and its structural formula is shown in Formula IV: Formula IV; In formula IV: R 4 is -H or -CH 3 , R 5 is -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 -, or -OCH 2 CH 2 -, n is the number of structural units, n = 38 - 152; the molecular weight of the unsaturated phosphated polyoxyethylene ether monomer is 2000 - 7000, and its molecular weight will significantly affect the performance of the polycarboxylate water reducer. Controlling its molecular weight can regulate the steric hindrance effect of different capabilities. After phosphorylating the end of the unsaturated polyoxyethylene ether monomer, the phosphate group has stronger electronegativity and chelating ability, and has higher affinity on the surface of cement and different types of inert powder particles, and can quickly reach a higher adsorption amount; at the same time, the phosphate group can form a stable complex with Ca 2+ in the cement, delay the hydration process of the cement, effectively improve the fluidity and slump retention performance of the concrete, and significantly improve the dispersion performance and viscosity reduction performance of the polycarboxylate water reducer; modifying with a glucosylated end increases the steric hindrance effect of the polyether side chain, hinders the intercalation adsorption of the clay on the polyether side chain, reduces the sensitivity of the water reducer to the clay, and improves the material adaptability; at the same time, the introduced glucose molecule has a good retarding effect, which is beneficial to maintaining the workability of the concrete at high temperature and for a long time, and improves the weather resistance adaptability of the water reducer.

[0024] Among them, the structural formula of the functional monomer is as shown in formula V: Formula V; In formula V: R 6 is -H or an alkyl group of C 1 ~C 3 , R 7 is an alkyl group of C 1 or C 3 , R 8 , R 9 , R 10 is -CH 3 , -CH 3 O, -CH 2 CH 3Any one of O; the functional monomer is one or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, methacryloyloxypropyltriethoxysilane, methacryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, (3-acryloyloxy)dimethylmethoxysilane, methacryloyloxymethyltriethoxysilane, methacryloyloxypropyltriethoxysilane. Introducing siloxane groups into the polycarboxylate superplasticizer can adjust the ratio of hydrophilic groups and hydrophobic groups, optimize the bubble structure of the concrete system, and significantly improve the homogeneity of the concrete; in addition, the siloxane groups significantly enhance the anchoring ability of the superplasticizer on the surface of cement and mineral admixture particles, effectively enhance the slump retention effect, and significantly improve the comprehensive performance of the concrete.

[0025] In the synthesis of the polycarboxylate superplasticizer of the present invention, by designing the molecular structure of the superplasticizer, the molecular weight and the degree of polymerization of the main chain can be controlled, thereby changing the side chain density and generating different steric hindrance effects; selecting to introduce functional group monomers with different surface activities for polymerization reaction, changing the hydrophilic-lipophilic balance value (HLB) of the superplasticizer, enabling the adsorption capacity, dispersion performance and viscosity reduction performance of the superplasticizer to be designed with gradient efficiency, ultimately realizing the functionalization of the polycarboxylate superplasticizer, and the comprehensive application effect in concrete will also be significantly improved; it has the advantages of high water reduction, long slump retention, low sensitivity, and reduction of concrete viscosity, and can effectively solve the problems of fluctuations in fluidity and state caused by unstable quality of concrete materials, and application problems such as unfavorable construction due to high viscosity of high-strength concrete; the unsaturated polyoxyethylene ether required in the synthesis includes common polyether types and has wide adaptability.

[0026] As Figure 1 shown, the preparation method of a low-sensitivity viscosity-reducing polycarboxylate superplasticizer disclosed in the present invention is divided into two parts. First, an unsaturated phosphated polyoxyethylene ether monomer is synthesized, and then a low-sensitivity viscosity-reducing polycarboxylate superplasticizer is synthesized by free radical copolymerization. The unsaturated polyoxyethylene ether and other raw materials used in the examples of the present invention are all commercially available ordinary chemical pure reagents. The preparation method includes the following specific steps: (I) Preparation of unsaturated phosphated polyoxyethylene ether monomer: Add the unsaturated polyoxyethylene ether monomer and glucose into a reaction vessel and mix them evenly. The unsaturated polyoxyethylene ether monomer is one or more of methyl allyl polyoxyethylene ether with a molecular weight of 2000 - 4000, isopentenol polyoxyethylene ether with a molecular weight of 3000 - 4000, 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 3000 - 5000, and ethylene glycol mono vinyl polyethylene glycol ether with a molecular weight of 3000 - 6000. Add an inhibitor, the inhibitor is hydroquinone, and the dosage of hydroquinone is 0.001 - 0.004% of the weight of the unsaturated polyoxyethylene ether monomer. Then, after heating to 60 - 80 °C, add a catalyst, the catalyst is benzenesulfonic acid or p-toluenesulfonic acid, and the dosage of the catalyst is 0.15 - 0.4% of the weight of glucose. Then, under a vacuum state with a vacuum degree of -0.080 to -0.096 MPa, heat to 95 - 110 °C, keep warm for 3 - 8 h, and then cool to 25 - 30 °C. Adjust the pH value to 7 - 8 with a 30% sodium hydroxide solution by mass fraction to obtain the end-glucosylated unsaturated polyoxyethylene ether monomer. Then, under a protective atmosphere, heat to 50 - 70 °C, and add polyphosphoric acid or P 2 O 5 in batches into the reaction vessel, stir and mix evenly, heat to 80 - 100 °C, carry out a phosphating reaction for 4 - 8 h, and cool to obtain the unsaturated phosphated polyoxyethylene ether monomer; among them, the polyphosphoric acid is one or more of tripolyphosphoric acid, tetrapolyphosphoric acid, pentapolyphosphoric acid, and hexapolyphosphoric acid, and its industrial grade content is 105 - 118% in terms of the mass fraction of phosphoric acid. In this step, the molar ratio of the unsaturated polyoxyethylene ether monomer, glucose, and polyphosphoric acid is 1:(1 - 1.1):(1 - 1.2), or the molar ratio of the unsaturated polyoxyethylene ether monomer, glucose, and P 2 O 5 is 1:(1 - 1.1):(0.5 - 0.6).

[0027] (2) Synthesize the polycarboxylate water reducer by radical copolymerization method: The prepared unsaturated phosphated polyoxyethylene ether monomer is added with an oxidant, a catalyst, a functional monomer and water and mixed evenly to form a primer solution; wherein, the oxidant is one or more of hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, and its dosage is 1-4% of the total molar amount of all unsaturated polymer monomers; the catalyst is one of ferrous sulfate, ferrous chloride, copper chloride, and its dosage is 0.006-0.01% of the total molar amount of unsaturated polymer monomers. Then the temperature is raised to 25-55°C and stirred and mixed evenly for 5-10 min; the unsaturated acid monomer, reducing agent, chain transfer agent and water are mixed evenly to prepare a dropping solution A; wherein, the reducing agent is one or more of L-ascorbic acid, sodium hypophosphite, sodium bisulfite, sodium metabisulfite, and its dosage is 0.2-1% of the total molar amount of unsaturated polymer monomers; the chain transfer agent is one or more of mercaptoethanol, mercaptoacetic acid, mercaptopropionic acid, and its dosage is 1.6-4.8% of the total molar amount of unsaturated polymer monomers. The unsaturated sulfonic acid or its salt monomer is mixed evenly with water to prepare a dropping solution B. Then the dropping solution A and the dropping solution B are gradually dropped into the primer solution simultaneously through a peristaltic pump for reaction, the dropping time is 0.5-2 h, and the dropping temperature is controlled at 25-55°C; wherein, the solid content of the primer solution and the dropping solution is 15-60%. Then, after heat preservation reaction for 1-2 h, a 30% sodium hydroxide solution by mass is added to adjust the pH value of the reaction solution to 6-8, and the polycarboxylate water reducer can be prepared.

[0028] The preparation method of the present invention has the advantages of simple preparation process, greatly shortened reaction time, high production efficiency, environmental protection, etc., and has great significance for promoting the research of polycarboxylate water reducers and improving the application technology level of concrete.

[0029] The present invention also discloses the application of a low-sensitivity viscosity-reducing polycarboxylate water reducer in a gel material. The dosage of the polycarboxylate water reducer is 0.05-0.5% by mass percentage of the total cementitious material, and its dosage is the dosage of pure solid; if the dosage of the polycarboxylate water reducer in the preparation of the cementitious material is too low, its performance will deteriorate, and if the dosage is too high, it will cause economic waste and the performance cannot be improved.

[0030] The following are specific examples of the present invention to further illustrate the technical solutions and effects of the present invention. The unsaturated polyoxyethylene ether and other raw materials used are all commercially available ordinary chemical pure reagents. In the examples of the present invention, the polymer molecular weight was measured by a miniDAWN Tristar aqueous gel permeation chromatograph (GPC, Wyatt Technology Corporation) equipped with a TSK-GEL SW (Tosoh Bioscience Co., Ltd.) chromatographic column. Mobile phase: 0.1 M NaNO 3 aqueous solution, flow rate: 1.0 mL / min, sample mass percentage concentration: 0.50%.

[0031] Example 1: The preparation method of the polycarboxylate water reducer in this example includes the following specific steps: (I) Preparation of unsaturated phosphated polyoxyethylene ether monomer: Add 0.2 mol of methyl allyl polyoxyethylene ether (molecular weight 2400) and 0.21 mol of glucose into a four-necked flask equipped with a stirrer and a thermometer, mix evenly, add hydroquinone with a weight of 0.002% of methyl allyl polyoxyethylene ether (molecular weight 2400), then heat up to 80 °C, and add p-toluenesulfonic acid with a weight of 0.2% of glucose. Then, under a vacuum state with a vacuum degree of -0.080 to -0.096 MPa, heat up to 105 °C, keep warm for 5 h, and then cool to room temperature. Adjust the pH value to 7 with a 30% sodium hydroxide solution by mass fraction to obtain a terminal glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, heat up the oil bath to 60 °C and keep it constant. Divide 0.22 mol of polyphosphoric acid with a content of 115% (Polyphosphoric acid, CAS No.: 8017-16-1, molecular formula: Hn+2PnO3n+1, product number P102919, ≥85% phosphate (as P205) basis, purchased from Aladdin Reagent (Shanghai) Co., Ltd.) into the reaction vessel in 3 equal portions, stir and mix evenly, heat up to 100 °C, carry out a phosphating reaction for 5.5 h, and obtain an unsaturated phosphated polyoxyethylene ether monomer after cooling. Mw measured by GPC is 2712.

[0032] (II) Synthesis of polycarboxylate water reducer by free radical copolymerization method: Add 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with an Mw molecular weight of 2712) into a three-necked flask equipped with a stirrer, add 0.01 mol of 3-methacryloxypropylmethyldimethoxysilane, 0.01 mol of hydrogen peroxide, 0.004 g of ferrous sulfate, and 271 g of water, mix evenly to form a base solution. Then heat up to 35 °C, stir and mix evenly for 5 - 10 min; mix 0.3 mol of acrylic acid, 0.0047 mol of L-ascorbic acid, 0.013 mol of mercaptoethanol, and 32 g of water evenly to prepare a dropping solution A. Mix 0.06 mol of sodium allylsulfonate and 28 g of water evenly to prepare a dropping solution B. Then simultaneously and gradually drop the dropping solution A and the dropping solution B into the base solution through a peristaltic pump for reaction. The dropping time is 1.5 h, and the dropping temperature is controlled at 35 °C. Then keep warm and react for 1 h, and add a 30% sodium hydroxide solution by mass fraction to adjust the pH value of the reaction solution to 7, and the polycarboxylate water reducer can be prepared. Mw measured by GPC is 26289.

[0033] Example 2: The preparation method of the polycarboxylate water reducer in this example includes the following specific steps: (I) Preparation of unsaturated phosphated polyoxyethylene ether monomer: Add 0.2 mol of 4-hydroxybutyl vinyl polyoxyethylene ether (molecular weight 3000) and 0.22 mol of glucose into a four-necked flask equipped with a stirrer and a thermometer, mix evenly, add hydroquinone with a weight of 0.003% of 4-hydroxybutyl vinyl polyoxyethylene ether (molecular weight 3000), then heat up to 70 °C, and add benzenesulfonic acid with a weight of 0.25% of glucose. Then, under a vacuum state with a vacuum degree of -0.080 to -0.096 MPa, heat up to 105 °C, keep warm for 4.5 h, and then cool to room temperature. Adjust the pH value to 7 with a sodium hydroxide solution with a mass fraction of 30% to obtain an end-glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, heat up the oil bath to 70 °C and keep it constant. Divide 0.24 mol of polyphosphoric acid with a content of 115% (Polyphosphoric acid, CAS No.: 8017-16-1, molecular formula: Hn+2PnO3n+1, product number P102919, ≥85% phosphate (as P2O5) basis, purchased from Aladdin Reagent (Shanghai) Co., Ltd.) into the reaction vessel in 3 equal portions, stir and mix evenly, heat up to 90 °C, carry out a phosphating reaction for 6.5 h, and after cooling, obtain an unsaturated phosphated polyoxyethylene ether monomer. The Mw measured by GPC is 3347.

[0034] (II) Synthesize polycarboxylate water reducer by free radical copolymerization method: Add 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with an Mw molecular weight of 3347) into a three-necked flask equipped with a stirrer, add 0.1 mol of methacryloxypropylmethyldiethoxysilane, 0.015 mol of ammonium persulfate, 0.003 g of ferrous chloride and 335 g of water, mix evenly to form a base solution. Then heat up to 25 °C and stir and mix evenly for 5 - 10 min; mix 0.45 mol of methacrylic acid, 0.0025 mol of sodium bisulfite, 0.015 mol of mercaptoethanol and 32 g of water evenly to prepare a dropping solution A. Mix 0.1 mol of sodium allylsulfonate and 28 g of water evenly to prepare a dropping solution B. Then, simultaneously and gradually drop the dropping solution A and the dropping solution B into the base solution through a peristaltic pump for reaction. The dropping time is 2.0 h, and the dropping temperature is controlled at 25 °C. Then, after holding the reaction for 2 h, add a sodium hydroxide solution with a mass fraction of 30% to adjust the pH value of the reaction solution to 7, and then the polycarboxylate water reducer can be prepared. The Mw measured by GPC is 39276.

[0035] Example 3: The preparation method of the polycarboxylate water reducer in this example includes the following specific steps: (I) Prepare unsaturated phosphated polyoxyethylene ether monomer: 0.2 mol of 4-hydroxybutyl vinyl polyoxyethylene ether (molecular weight 4000) and 0.21 mol of glucose were added to a four-necked flask equipped with a stirrer and a thermometer and mixed evenly. Hydroquinone with a weight of 0.0025% of 4-hydroxybutyl vinyl polyoxyethylene ether (molecular weight 4000) was added. Then, after heating to 60 °C, p-toluenesulfonic acid with a weight of 0.3% of glucose was added. Subsequently, it was heated to 110 °C under a vacuum state with a vacuum degree of -0.080 to -0.096 MPa, kept warm for 4 h, and then cooled to room temperature. The pH value was adjusted to 7 by a sodium hydroxide solution with a mass fraction of 30% to obtain an end-glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, the oil bath was heated to 50 °C and kept constant. 0.22 mol of polyphosphoric acid with a content of 115% (Polyphosphoric acid, CAS No.: 8017-16-1, molecular formula: Hn+2PnO3n+1, product number P102919, ≥85% phosphate (as P205) basis, purchased from Aladdin Reagent (Shanghai) Co., Ltd.) was evenly added to the reaction vessel in 3 portions, stirred and mixed evenly, heated to 80 °C, and subjected to a phosphating reaction for 7.5 h. After cooling, an unsaturated phosphated polyoxyethylene ether monomer was obtained, and Mw measured by GPC was 4417.

[0036] (II) Synthesizing a polycarboxylate water reducer by radical copolymerization: 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with a Mw molecular weight of 4417) was added to a three-necked flask equipped with a stirrer. 0.12 mol of 3-(methacryloyloxy)propyltrimethoxysilane, 0.038 mol of potassium persulfate, 0.005 g of copper chloride, and 440 g of water were added and mixed evenly to form a bottoming solution. Then, it was heated to 30 °C and stirred and mixed evenly for 5 - 10 min; 0.5 mol of acrylic acid, 0.1 mol of maleic acid, 0.0077 mol of sodium bisulfite, 0.045 mol of mercaptopropionic acid, and 32 g of water were mixed evenly to prepare a dropping solution A. 0.15 mol of allylsulfonic acid sodium and 28 g of water were mixed evenly to prepare a dropping solution B. Then, the dropping solution A and the dropping solution B were simultaneously and gradually added dropwise into the bottoming solution through a peristaltic pump for reaction. The dropping time was 0.5 h, and the dropping temperature was controlled at 30 °C. Then, after holding the reaction for 1 h, a sodium hydroxide solution with a mass fraction of 30% was added to adjust the pH value of the reaction solution to 7, and thus a polycarboxylate water reducer was prepared. Mw measured by GPC was 48695.

[0037] Example 4: The preparation method of the polycarboxylate water reducer in this example includes the following specific steps: (I) Preparing an unsaturated phosphated polyoxyethylene ether monomer: Add 0.2 mol of isopentenyl alcohol polyoxyethylene ether (molecular weight 3000) and 0.21 mol of glucose into a four-necked flask equipped with a stirrer and a thermometer, mix them evenly, add hydroquinone with a weight of 0.003% of isopentenyl alcohol polyoxyethylene ether (molecular weight 3000), then heat up to 65 °C, and add p-toluenesulfonic acid with a weight of 0.35% of glucose. Then, under a vacuum state with a vacuum degree of -0.080~-0.096 MPa, heat up to 100 °C, keep warm for 6 h, and then cool to room temperature. Adjust the pH value to 7 with a 30% sodium hydroxide solution by mass fraction to obtain the terminal glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, heat up the oil bath to 65 °C and keep it constant temperature, and add 0.1 mol of P 2 O 5 Average it and add it to the reaction vessel in 3 times, stir and mix evenly, heat up to 100 °C, carry out the phosphating reaction for 7 h, and after cooling, obtain the unsaturated phosphated polyoxyethylene ether monomer. The Mw measured by GPC is 3324.

[0038] (II) Synthesize the polycarboxylate superplasticizer by free radical copolymerization method: Add 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with Mw molecular weight of 3324) into a three-necked flask equipped with a stirrer, add 0.08 mol of γ-methacryloyloxypropylmethyldimethoxysilane, 0.02 mol of ammonium persulfate, 0.006 g of ferrous sulfate and 270 g of water, mix them evenly to form a bottoming solution. Then heat up to 40 °C, stir and mix evenly for 5~10 min; mix 0.35 mol of acrylic acid, 0.0047 mol of L-ascorbic acid, 0.02 mol of mercaptoacetic acid and 43 g of water evenly to prepare a dropping solution A. Mix 0.14 mol of sodium methallylsulfonate and 37 g of water evenly to prepare a dropping solution B. Then, simultaneously and gradually add the dropping solution A and the dropping solution B into the bottoming solution through a peristaltic pump for reaction. The dropping time is 2.0 h, and the dropping temperature is controlled at 45 °C. Then, after keeping warm and reacting for 1.5 h, add a 30% sodium hydroxide solution by mass fraction to adjust the pH value of the reaction solution to 7, and the polycarboxylate superplasticizer can be prepared. The Mw measured by GPC is 36375.

[0039] Example 5: The preparation method of the polycarboxylate superplasticizer in this example includes the following specific steps: (I) Prepare the unsaturated phosphated polyoxyethylene ether monomer: Add 0.2 mol of ethylene glycol mono vinyl polyethylene glycol ether (with a molecular weight of 4000) and 0.22 mol of glucose into a four-necked flask equipped with a stirrer and a thermometer, mix them evenly, add hydroquinone with a weight of 0.0035% of ethylene glycol mono vinyl polyethylene glycol ether (with a molecular weight of 4000), then heat up to 65 °C, and add benzenesulfonic acid with a weight of 0.25% of glucose. Then, under a vacuum state with a vacuum degree of -0.080 to -0.096 MPa, heat up to 110 °C, keep warm for 7.5 h, and then cool to room temperature. Adjust the pH value to 7 with a 30% sodium hydroxide solution by mass fraction to obtain an end-glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, heat up the oil bath to 50 °C and keep it constant. Add 0.24 mol of polyphosphoric acid (Polyphosphoric acid, CAS No.: 8017-16-1, molecular formula: Hn+2PnO3n+1, product number P102919, ≥85% phosphate (as P205) basis, purchased from Aladdin Reagent (Shanghai) Co., Ltd.) with a content of 115% into the reaction vessel in 3 equal portions, stir and mix evenly, heat up to 100 °C, carry out a phosphating reaction for 6 h, and after cooling, obtain an unsaturated phosphated polyoxyethylene ether monomer. The Mw measured by GPC is 4412.

[0040] (2) Synthesize a polycarboxylate water reducer by free radical copolymerization method: Add 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with a Mw molecular weight of 4412) into a three-necked flask equipped with a stirrer, add 0.1 mol of methacryloyloxymethyltriethoxysilane, 0.014 mol of sodium persulfate, 0.0048 g of ferrous chloride and 340 g of water, mix them evenly to form a bottoming solution. Then heat up to 45 °C, stir and mix evenly for 5 - 10 min; mix 0.4 mol of itaconic acid, 0.0036 mol of sodium metabisulfite, 0.017 mol of mercaptoacetic acid and 45 g of water evenly to prepare a dropping solution A. Mix 0.15 mol of allylsulfonic acid sodium and 32 g of water evenly to prepare a dropping solution B. Then, simultaneously and gradually add the dropping solution A and the dropping solution B into the bottoming solution through a peristaltic pump for reaction. The dropping time is 1.5 h, and the dropping temperature is controlled at 45 °C. Then keep warm and react for 1 h, and add a 30% sodium hydroxide solution by mass fraction to adjust the pH value of the reaction solution to 7, and then the polycarboxylate water reducer can be prepared. The Mw measured by GPC is 45478.

[0041] Example 6: The preparation method of the polycarboxylate water reducer in this example includes the following specific steps: (1) Prepare an unsaturated phosphated polyoxyethylene ether monomer: Add 0.2 mol of ethylene glycol mono vinyl polyethylene glycol ether (with a molecular weight of 6000) and 0.2 mol of glucose into a four-necked flask equipped with a stirrer and a thermometer, mix evenly, add hydroquinone with a weight of 0.003% of ethylene glycol mono vinyl polyethylene glycol ether (with a molecular weight of 6000), then heat up to 60 °C, and add p-toluenesulfonic acid with a weight of 0.35% of glucose. Then, under a vacuum state with a vacuum degree of -0.080~-0.096 MPa, heat up to 100 °C, keep warm for 5.5 h, and then cool to room temperature. Adjust the pH value to 7 with a sodium hydroxide solution with a mass fraction of 30% to obtain an end-glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, heat up the oil bath to 50 °C and keep it constant, and add 0.12 mol of P 2 O 5 Add it to the reaction vessel in 3 equal portions on average, stir and mix evenly, heat up to 90 °C, carry out a phosphating reaction for 8 h, and obtain an unsaturated phosphated polyoxyethylene ether monomer after cooling. The Mw measured by GPC is 6327.

[0042] (II) Synthesize polycarboxylate superplasticizer by free radical copolymerization method: Add 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with a Mw molecular weight of 4327) into a three-necked flask equipped with a stirrer, add 0.06 mol of methacryloxypropyltriethoxysilane, 0.02 mol of hydrogen peroxide, 0.006 g of ferrous sulfate and 400 g of water, mix evenly to form a primer solution. Then heat up to 55 °C, stir and mix evenly for 5~10 min; mix 0.4 mol of fumaric acid, 0.003 mol of sodium hypophosphite, 0.027 mol of mercaptoethanol and 40 g of water evenly to prepare a dropping solution A. Mix 0.16 mol of allylsulfonic acid sodium and 35 g of water evenly to prepare a dropping solution B. Then, simultaneously and gradually add the dropping solution A and the dropping solution B into the primer solution through a peristaltic pump for reaction. The dropping time is 0.5 h, and the dropping temperature is controlled at 55 °C. Then, after keeping warm and reacting for 1 h, add a sodium hydroxide solution with a mass fraction of 30% to adjust the pH value of the reaction solution to 7, and the polycarboxylate superplasticizer can be prepared. The Mw measured by GPC is 57845.

[0043] Example 7: The preparation method of the polycarboxylate superplasticizer in this example includes the following specific steps: (I) Prepare unsaturated phosphated polyoxyethylene ether monomer: Add 0.2 mol of methallyl polyoxyethylene ether (molecular weight 3000) and 0.21 mol of glucose into a four-necked flask equipped with a stirrer and a thermometer, mix evenly, add hydroquinone with a weight of 0.004% of methallyl polyoxyethylene ether (molecular weight 3000), then heat up to 65 °C, and add p-toluenesulfonic acid with a weight of 0.25% of glucose. Then, under a vacuum state with a vacuum degree of -0.080 to -0.096 MPa, heat up to 110 °C, keep the temperature for 6 h, and then cool to room temperature. Adjust the pH value to 7 with a 30% sodium hydroxide solution by mass fraction to obtain the terminal glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, heat up the oil bath to 60 °C and keep it constant. Divide 0.21 mol of polyphosphoric acid with a content of 115% (Polyphosphoric acid, CAS No.: 8017-16-1, molecular formula: Hn+2PnO3n+1, product number P102919, ≥85% phosphate (as P2O5) basis, purchased from Aladdin Reagent (Shanghai) Co., Ltd.) into the reaction vessel in 3 equal portions, stir and mix evenly, heat up to 85 °C, carry out the phosphating reaction for 8 h, and after cooling, obtain the unsaturated phosphated polyoxyethylene ether monomer. The Mw measured by GPC is 3378.

[0044] (II) Synthesize the polycarboxylate water reducer by radical copolymerization method: Add 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with a Mw molecular weight of 3378) into a three-necked flask equipped with a stirrer, add 0.006 mol of (3-acryloyloxy) dimethylmethoxysilane, 0.027 mol of hydrogen peroxide, 0.005 g of copper chloride and 330 g of water, mix evenly to form a bottoming solution. Then heat up to 35 °C, stir and mix evenly for 5 - 10 min; mix 0.6 mol of acrylic acid, 0.007 mol of L-ascorbic acid, 0.029 mol of mercaptopropionic acid and 40 g of water evenly to prepare a dropping solution A. Mix 0.2 mol of sodium methallylsulfonate and 30 g of water evenly to prepare a dropping solution B. Then gradually drop the dropping solution A and the dropping solution B into the bottoming solution simultaneously through a peristaltic pump for reaction. The dropping time is 2 h, and the dropping temperature is controlled at 35 °C. Then keep the temperature for reaction for 1.5 h, and then add a 30% sodium hydroxide solution by mass fraction to adjust the pH value of the reaction solution to 7, and the polycarboxylate water reducer can be prepared. The Mw measured by GPC is 42785.

[0045] Example 8: The preparation method of the polycarboxylate water reducer in this example includes the following specific steps: (I) Prepare the unsaturated phosphated polyoxyethylene ether monomer: Add 0.2 mol of isopentenyl alcohol polyoxyethylene ether (molecular weight 3000) and 0.21 mol of glucose into a four-necked flask equipped with a stirrer and a thermometer, mix them evenly, add hydroquinone with a weight of 0.003% of isopentenyl alcohol polyoxyethylene ether (molecular weight 3000), then heat up to 70 °C, and add p-toluenesulfonic acid with a weight of 0.35% of glucose. Then, under a vacuum state with a vacuum degree of -0.080 to -0.096 MPa, heat up to 105 °C, keep the temperature for 6.5 h, and then cool to room temperature. Adjust the pH value to 7 with a 30% sodium hydroxide solution by mass fraction to obtain the terminal glucosylated unsaturated polyoxyethylene ether monomer. Then, under a nitrogen protection atmosphere, heat up the oil bath to 55 °C and keep it constant. Add 0.24 mol of polyphosphoric acid with a content of 115% (Polyphosphoric acid, CAS No.: 8017-16-1, molecular formula: Hn+2PnO3n+1, product number P102919, ≥85% phosphate (as P2O5) basis, purchased from Aladdin Reagent (Shanghai) Co., Ltd.) into the reaction vessel in three equal portions, stir and mix evenly, heat up to 90 °C, carry out the phosphating reaction for 7 h, and after cooling, obtain the unsaturated phosphated polyoxyethylene ether monomer. The Mw measured by GPC is 3386.

[0046] (2) Synthesize the polycarboxylate superplasticizer by radical copolymerization method: Add 0.1 mol of unsaturated phosphated polyoxyethylene ether monomer (with a Mw molecular weight of 3386) into a three-necked flask equipped with a stirrer, add 0.08 mol of 3-(methacryloyloxy)propyltrimethoxysilane, 0.02 mol of hydrogen peroxide, 0.004 g of ferrous sulfate, and 340 g of water, mix them evenly to form a base solution. Then heat up to 25 °C, stir and mix evenly for 5 - 10 min; mix 0.3 mol of acrylic acid, 0.15 mol of maleic acid, 0.0027 mol of L-ascorbic acid, 0.022 mol of mercaptoethanol, and 30 g of water evenly to prepare a dropping solution A. Mix 0.12 mol of allylsulfonic acid sodium and 25 g of water evenly to prepare a dropping solution B. Then, simultaneously and gradually add the dropping solution A and the dropping solution B into the base solution through a peristaltic pump for reaction. The dropping time is 1.5 h, and the dropping temperature is controlled at 25 °C. Then keep the temperature for reaction for 1.5 h, and add a 30% sodium hydroxide solution by mass fraction to adjust the pH value of the reaction solution to 7, and the polycarboxylate superplasticizer can be prepared. The Mw measured by GPC is 52435.

[0047] Comparative Example 1: In Comparative Example 1, a commercially available high-performance polycarboxylate superplasticizer is used, and the Mw measured by GPC is 30635.

[0048] Comparative Example 2: 0.1 mol of methyl allyl polyoxyethylene ether (Mw molecular weight is 2400), 0.005 mol of hydrogen peroxide and 240 g of water were added to a three-necked flask equipped with a stirrer and mixed evenly. Then the temperature was raised to 40 °C and stirred evenly for 5 - 10 min; 0.45 mol of acrylic acid, 0.0011 mol of L-ascorbic acid, 0.017 mol of mercaptoethanol and 60 g of water were mixed to prepare a dropping solution. Under continuous stirring at a constant temperature of 40 °C, the dropping solution was added dropwise into the three-necked flask. The dropping time was 2 h. After the dropping was completed, the reaction was kept warm for 1 h. A sodium hydroxide solution with a mass fraction of 30% was added to adjust the pH value of the reaction solution to 7, and then the ordinary polycarboxylate superplasticizer was prepared in the laboratory. The Mw measured by GPC was 27864.

[0049] The polycarboxylate superplasticizer samples obtained in Examples 1 - 8 and Comparative Examples 1 - 2 of the present invention were applied to prepare concrete cementitious materials. Among them, the cement used can be Hulin P.O42.5, Hulin P.O52.5, Conch P.O42.5, and reference P.O42.5 cement. The mineral powder is the S95 type mineral powder produced by a factory in the south of the Yangtze River, the fly ash is the grade I fly ash produced by a factory in Jiangsu, the sand is medium sand with a fineness modulus M = 2.6, and the stone is basalt with a continuous gradation of 5 - 20 mm particle size.

[0050] Application Example 1: According to the methods specified in the "Standard Test Method for Properties of Ordinary Concrete Mixtures" GB / T 50080 - 2016, the air content, slump and spread of concrete were measured, and according to "Concrete Admixtures" GB 8076 - 2008, the water reduction rate of the samples was measured. The polycarboxylate superplasticizer samples obtained in Examples 1 - 8 and Comparative Examples 1 - 2 of the present invention had an admixture amount of 0.13% in the corresponding concrete cementitious materials. The water consumption was adjusted to control the initial slump of the concrete to 22 ± 1 cm. The weight mix ratio of the concrete was: 250 parts by weight of Hulin P.O42.5 cement, 50 parts by weight of mineral powder, 60 parts by weight of fly ash, 770 parts by weight of sand, 440 parts by weight of large stones, 495 parts by weight of medium stones, 165 parts by weight of small stones and 160 parts by weight of water. The test results of the concrete performance are shown in Table 1.

[0051] Table 1 Test results of the concrete performance prepared in Examples 1 - 8 and Comparative Examples 1 - 2 of the present invention: 。

[0052] As can be seen from Table 1, in the case where the dosages of polycarboxylate water reducers and the air contents in Examples 1-8 of the present invention are the same as those in Comparative Examples 1-2, the average water reduction rate can reach 43.6%, while the water reduction rate of the comparative examples is only about 35.8%. The water reduction rate of the examples is 7.8% higher than that of the comparative examples, indicating that the low-sensitivity viscosity-reducing polycarboxylate water reducer of the examples of the present invention has a water reduction performance improvement of more than 20% compared with the existing polycarboxylate water reducer products. In addition, the slump and spread of the concrete mixed with the low-sensitivity viscosity-reducing polycarboxylate water reducer of the examples of the present invention change little after 60 minutes compared with the initial stage, and both the initial and 60-minute slump and spread are better than those of the concrete mixed with the existing polycarboxylate products. From the air content results of the concrete in the examples and comparative examples of the present invention, the two are not much different, indicating that the improvement in water reduction and slump retention ability is not caused by excessive gas introduction, indicating that the low-sensitivity viscosity-reducing polycarboxylate water reducer of the examples of the present invention has excellent water reduction performance and slump retention performance.

[0053] Application Example 2: Referring to GB / T 8077-2023 "Test Methods for the Homogeneity of Concrete Admixtures", the fluidity of polycarboxylate water reducers at different cements and different temperatures was measured. To study the adaptability sensitivity of the low-sensitivity viscosity-reducing polycarboxylate water reducers in Examples 1-8 of the present invention and the conventional polycarboxylate water reducers in Comparative Examples 1-2 to different cements, neat paste tests were carried out on Portland cements produced by different manufacturers at different temperatures, fixing the dosage of polycarboxylate water reducer at 0.12%, and fixing the water-cement ratio at 0.29. The test results of the sensitivity of the polycarboxylate water reducer samples in Examples 1-8 and Comparative Examples 1-2 of the present invention to cement and temperature are shown in Table 2.

[0054] Table 2 Test results of the sensitivity of the polycarboxylate water reducer samples in Examples 1-8 and Comparative Examples 1-2 of the present invention to cement and temperature: 。

[0055] As can be seen from Table 2, although there are differences between different cements, the overall change trend is the same, and the fluidity differences of the low-sensitivity viscosity-reducing polycarboxylate water reducers in the examples of the present invention in different cements are not significant. The fluctuation of the neat paste fluidity of the examples of the present invention at different ambient temperatures is significantly smaller than that of the comparative examples, indicating that the low-sensitivity viscosity-reducing polycarboxylate water reducers of the examples of the present invention have good adaptability and low sensitivity to different cements compared with the existing polycarboxylate product water reducers.

[0056] Application Example 3: Montmorillonite is a typical clay, and its adsorption capacity for polycarboxylate water reducers is much greater than that of cement. In the experiment, the method of adding montmorillonite to cement was used to simulate the clay content in sand and gravel materials, and the tolerance of the polycarboxylate water reducers in Examples 1-8 and Comparative Examples 1-2 of the present invention to clay was detected. According to GB / T 8077-2023 "Test Methods for the Homogeneity of Concrete Admixtures", the fluidity of the neat cement paste was measured. Different masses of montmorillonite were used to replace the corresponding masses of cement, the water-cement ratio was fixed at 0.29, and the dosage of the water reducer was adjusted to make the initial fluidity of the neat cement paste 260 mm. The test results of the anti-clay performance of the polycarboxylate water reducer samples in Examples 1-8 and Comparative Examples 1-2 of the present invention are shown in Table 3.

[0057] Table 3 Test results of the anti-clay performance of the polycarboxylate water reducer samples in Examples 1-8 and Comparative Examples 1-2 of the present invention: ; Note: "--" indicates no fluidity.

[0058] As can be seen from Table 3, when 0.5% and 1% of montmorillonite were added, the fluidity of the neat cement paste in Examples 1-8 of the present invention decreased by about 5.7% and 17.1% respectively, while the fluidity of the neat cement paste in Comparative Examples 1-2 decreased by more than 32% until it lost fluidity, indicating that the low-sensitivity viscosity-reducing polycarboxylate water reducers in Examples 1-8 of the present invention have good tolerance to montmorillonite, and this product has significant competitive advantages in some application scenarios with a large clay content in sand and gravel aggregates.

[0059] Application Example 4: Blast furnace slag powder and fly ash are both commonly used admixtures in concrete. The sensitivity and adaptability of different polycarboxylate water reducers to mineral fine powder materials have a significant impact on the performance of concrete. According to the method specified in GB 8076-2008 "Concrete Admixtures", the influence of the polycarboxylate water reducers in Examples 1-8 and Comparative Examples 1-2 of the present invention on the performance of concrete under different dosages of admixtures (blast furnace slag powder, fly ash) was detected. The mass mix ratio of concrete 1: 226 parts by weight of cement, 84 parts by weight of blast furnace slag powder, 75 parts by weight of fly ash, 760 parts by weight of sand, 1090 parts by weight of stone, 165 parts by weight of water; the mass mix ratio of concrete 2: 152 parts by weight of cement, 128 parts by weight of blast furnace slag powder, 105 parts by weight of fly ash, 760 parts by weight of sand, 1090 parts by weight of stone, 165 parts by weight of water. According to the method specified in GB / T 50080-2016 "Standard Test Method for Properties of Ordinary Concrete Mixtures", the slump and spread of the concrete were measured. The test results of the performance of concrete with different mix ratios of the polycarboxylate water reducer samples in Examples 1-8 and Comparative Examples 1-2 of the present invention are shown in Table 4.

[0060] Table 4 Test results of the performance of concrete with different mix ratios of polycarboxylate superplasticizer samples in Examples 1-8 and Comparative Examples 1-2 of the present invention: 。

[0061] As can be seen from Table 4, under two different concrete mix ratios, with the dosage of the polycarboxylate superplasticizer remaining unchanged in the two tests, the fluctuations in the slump flow and slump of the concrete in Examples 1-8 of the present invention are significantly smaller than those in Comparative Examples 1-2 under the two different mix ratios. Moreover, under the concrete mass mix ratio 2 (with high amounts of mineral powder and fly ash), Comparative Examples 1-2 showed slow initial dispersion of the concrete and a phenomenon of re-increase at 30 minutes, while the state of Examples 1-8 of the present invention was stable and there was no re-increase phenomenon, indicating that the low-sensitivity viscosity-reducing polycarboxylate superplasticizer in Examples 1-8 of the present invention has lower sensitivity and excellent adaptability to changes in the dosage of admixtures (mineral powder, fly ash).

[0062] Application Example 5: According to the method specified in GB 8076-2008 "Concrete Admixtures", the effects of the polycarboxylate superplasticizer in Examples 1-8 and Comparative Examples 1-2 of the present invention on high-strength concrete were detected. The dosage of the polycarboxylate superplasticizer was adjusted to make the initial slump of the concrete between 24 ± 1 cm. The concrete mass mix ratio was: 380 parts by weight of cement, 105 parts by weight of mineral powder, 82 parts by weight of fly ash, 17 parts by weight of silica fume, 745 parts by weight of sand, 1130 parts by weight of stone, and 145 parts by weight of water. Referring to GB / T50080-2016 "Standard Test Method for Properties of Fresh Concrete", the properties of the fresh concrete were tested. The evacuation time of the fresh concrete was measured using an inverted slump cone. The concrete viscosity was quantified by measuring the initial flow emptying time with an inverted slump cone. The specific method was: Invert the slump cone, seal the bottom, fill it with concrete and level it (generally, fix the inverted slump cone on a bracket with the bottom 50 cm above the ground), quickly slide open the bottom cover, and use a stopwatch to measure the evacuation time of the concrete. The test results of the high-strength concrete performance of Examples 1-8 and Comparative Examples 1-2 of the present invention are shown in Table 5.

[0063] Table 5 Test results of the performance of high-strength concrete in Examples 1-8 and Comparative Examples 1-2 of the present invention: 。

[0064] As can be seen from Table 5, when the dosage of the polycarboxylate water reducer in Examples 1-8 of the present invention is about 22% lower than that in Comparative Examples 1-2, the initial slump / spread of the concrete in the examples of the present invention is similar to that in the comparative examples, and the slump and spread after 60 minutes are better than those in the comparative examples, indicating that the low-sensitivity viscosity-reducing polycarboxylate water reducer of the present invention has excellent properties of high water reduction and high slump retention. When the air content of Examples 1-8 of the present invention is similar to that of Comparative Examples 1-2, the initial flow emptying time of the high-strength concrete in Examples 1-8 of the present invention is close to 10 seconds, which is much less than 28-32 seconds in Comparative Examples 1-2, indicating that the low-sensitivity viscosity-reducing polycarboxylate water reducer of the present invention can effectively reduce the viscosity of high-strength concrete, improve the workability of concrete, and is conducive to pumping concrete in construction. This polycarboxylate water reducer product has broad application prospects in the high-strength concrete market.

[0065] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A low-sensitivity viscosity-reducing polycarboxylate water-reducing agent, characterized in that: The structural formula of the polycarboxylate water reducer is shown in Formula I: Formula I; In formula I: R1 is -H or -COOH, R2 is -H, -CH3 or -CH2COOH, R3 is -H or -CH3, M1 is Na, R4 is H or CH3, R5 is -CH2-, -CH2CH2-, -CH2CH2CH2CH2- or -OCH2CH2-, R6 is -H or CH3, R7 is C1 or C3 alkyl, R8, R9, R 10 It is any one of -CH3, -CH3O, and -CH2CH3O; a, b, c, d, and n represent the molar number of each repeating unit; and the molecular weight of the polycarboxylate water-reducing agent is 20,000 to 60,000 Da.

2. The low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to claim 1, characterized in that: The polycarboxylic acid water reducer is prepared by free radical copolymerization of unsaturated acid monomers, unsaturated sulfonate monomers, unsaturated phosphated polyoxyethylene ether monomers and functional monomers according to a molar ratio of a:b:c:d=(3-6):(0.5-2):1:(0.06-1.2).

3. The low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to claim 2, characterized in that: The structural formula of the unsaturated acid monomer is shown in Formula II: Formula II; In formula II: R1 is -H or -COOH, R2 is -H, -CH3 or -CH2COOH; wherein, if R1 is -COOH, R2 is -H; if R2 is -CH2COOH, R1 is -H; The unsaturated acid monomer is one or a combination of several of acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid in any proportion.

4. The low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to claim 2, characterized in that: The structural formula of the unsaturated sulfonic acid or its salt monomer is shown in Formula III: Formula III; In formula III: R3 is -H or -CH3, M1 is Na; The unsaturated sulfonate monomer is one of sodium allyl sulfonate and sodium methyl allyl sulfonate or a combination of the two in any proportion.

5. The low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to claim 2, characterized in that: The unsaturated phosphated polyoxyethylene ether monomer is a macromolecular monomer having a polyether long chain structure and the terminal is glycosylated and then phosphorylated, and its terminal group contains an unsaturated carbon-carbon double bond, and its structural formula is shown in Formula IV: Formula IV; In formula IV, R4 is -H or -CH3, R5 is -CH2-, -CH2CH2-, -CH2CH2CH2CH2- or -OCH2CH2-, n is the number of structural units, n=38~152; the molecular weight of the unsaturated phosphated polyoxyethylene ether monomer is 2000~7000.

6. The low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to claim 2, characterized in that: The functional monomer structural formula is shown in Formula V: Formula V; In Formula V: R6 is -H or a C1-C3 alkyl group, R7 is a C1 or C3 alkyl group, R8, R9, R 10 Any one of -CH3, -CH3O, -CH2CH3O; The functional monomer is one or more of 3-(methacryloxy)propyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, (3-acryloxy)dimethylmethoxysilane, methacryloxymethyltriethoxysilane, and methacryloxypropyltriethoxysilane.

7. A method for preparing a low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: Step 1: preparing an unsaturated phosphated polyoxyethylene ether monomer: adding an unsaturated polyoxyethylene ether monomer and glucose into a reaction vessel and mixing evenly, adding an inhibitor, heating to 60-80°C, adding a catalyst and heating to 95-110°C under vacuum, keeping warm for 3-8 hours, cooling to 25-30°C, adjusting the pH value to 7-8, and obtaining a terminal glucose-glycosylated unsaturated polyoxyethylene ether monomer; then heating to 50-70°C under a protective atmosphere, adding polyphosphoric acid or P2O5 in batches into a reaction vessel and stirring and mixing, heating to 80-100°C, phosphating for 4-8 hours, and cooling to obtain an unsaturated phosphated polyoxyethylene ether monomer; Step 2: Add an oxidant, a catalyst, a functional monomer and water to the prepared unsaturated phosphated polyoxyethylene ether monomer and mix them evenly to form a primer, heat it to 25-55°C, and stir and mix for 5-10 minutes; mix the unsaturated acid monomer, the reducing agent, the chain transfer agent and water evenly to prepare a drop liquid A; mix the unsaturated sulfonic acid or its salt monomer with water evenly to prepare a drop liquid B; drop liquid A and drop liquid B are gradually added to the primer by a peristaltic pump at the same time for reaction, the drop time is 0.5-2h, and the drop temperature is controlled at 25-55°C; wherein the solid content of the primer and the drop liquid is 15-60%; then, after keeping the reaction warm for 1-2h, an alkaline neutralizer is added to adjust the pH value of the reaction liquid to 6-8 to obtain the polycarboxylic acid water reducer.

8. The method for preparing the low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to claim 7, characterized in that: In step 1, the molar ratio of the unsaturated polyoxyethylene ether monomer, glucose, and polyphosphoric acid is 1:(1-1.1):(1-1.2), or the molar ratio of the unsaturated polyoxyethylene ether monomer, glucose, and P2O5 is 1:(1-1.1):(0.5-0.6); The polymerization inhibitor is hydroquinone, and the amount of hydroquinone used is 0.001-0.004% of the weight of the unsaturated polyoxyethylene ether monomer; The catalyst is benzenesulfonic acid or p-toluenesulfonic acid, and the amount of the catalyst is 0.15-0.4% of the weight of glucose; The vacuum degree of the vacuum state is -0.080~-0.096MPa; The alkali solution for adjusting pH is a 30% by mass sodium hydroxide solution; The polyphosphoric acid is one or more of tripolyphosphoric acid, tetrapolyphosphoric acid, pentapolyphosphoric acid and hexapolyphosphoric acid, and its industrial grade content is 105-118% based on the mass fraction of phosphoric acid; The unsaturated polyoxyethylene ether monomer is one or more of methyl allyl polyoxyethylene ether with a molecular weight of 2000-4000, isopentanol polyoxyethylene ether with a molecular weight of 3000-4000, 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 3000-5000, and ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 3000-6000.

9. The method for preparing the low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to claim 7, characterized in that: In step 2, the oxidant is one or more of hydrogen peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate, and the amount thereof is 1-4% of the total molar amount of all unsaturated polymerizable monomers; The reducing agent is one or more of L-ascorbic acid, sodium hypophosphite, sodium bisulfite, and sodium pyrosulfite, and its amount is 0.2-1% of the total molar amount of the unsaturated polymerization monomer; The chain transfer agent is one or more of mercaptoethanol, thioglycolic acid, and mercaptopropionic acid, and its usage is 1.6-4.8% of the total molar amount of the unsaturated polymerization monomer; The catalyst used in the polymerization reaction is one of ferrous sulfate, ferrous chloride and cupric chloride, and its amount is 0.006-0.01% of the total molar amount of the unsaturated polymerization monomer; The alkaline neutralizing agent is a sodium hydroxide solution with a mass fraction of 30%.

10. Use of the low-sensitivity viscosity-reducing polycarboxylate water-reducing agent according to any one of claims 1 to 6 in a gel material, characterized in that: The polycarboxylate water-reducing agent is added in an amount of 0.05-0.5% by mass of the total cementitious material, and the amount is a pure solid amount.

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