A low-sensitivity ester polycarboxylate slump-retaining agent, its preparation method and application

Abstract

The present invention relates to the technical field of concrete admixtures, and particularly relates to a low-sensitivity ester-based polycarboxylate slump-retaining agent and its preparation method and application. The low-sensitivity ester-based polycarboxylate slump-retaining agent includes a polyester structural unit, a carboxylic acid structural unit, an esterification functional structural unit, and a carboxylic acid hydroxy ester structural unit. The key of the present invention is to carry out free radical copolymerization of an esterification functional monomer and a carboxylic acid hydroxy ester monomer with specific structures with an unsaturated polyester monomer and an unsaturated carboxylic acid monomer. The resulting polycarboxylate slump-retaining agent can reduce the sensitivity of concrete, reduce slump loss, improve the workability of concrete, improve the anti-slurry performance, enhance the workability, reduce the sensitivity to changes in raw materials, facilitate the pumping of manufactured sand concrete, pumped concrete, etc., realize the pumping construction of concrete, and effectively improve the concrete construction efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete admixtures, and particularly relates to a low-sensitivity ester-based polycarboxylate slump-retaining agent, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of the construction industry, the market demand for ready-mixed concrete is in short supply, and the development of concrete admixtures has entered a new era. The consumption of concrete and cement is increasing continuously. As one of the important admixtures for concrete, polycarboxylate slump-retaining agents have also become a hot spot in the research and development of concrete.

[0003] Polycarboxylate slump-retaining agents are commonly used functional admixtures in the production of concrete. Generally speaking, it is a water-soluble polymer with a comb-like structure obtained by free radical polymerization of monomers such as unsaturated long-chain polyethers, hydroxyacrylate esters (such as hydroxyethyl / methylpropyl acrylate, etc.) and a small amount of unsaturated carboxylic acids. In the alkaline slurry of fresh concrete, the ester group of the polycarboxylate slump-retaining agent undergoes hydrolysis to release negatively charged acrylic acid / methacrylic acid structural units, etc., which prompts the polycarboxylate slump-retaining agent molecules to gradually adsorb onto the surface of the exposed cement particles, thereby producing a new dispersion effect and achieving the effect of maintaining the fluidity of fresh concrete, that is, slump retention.

[0004] Although the excellent slump retention performance of polycarboxylate slump-retaining agents has been widely recognized in the industry at present, due to reasons such as the increasingly poor quality of sand and stone materials (high mud content and stone powder content), polycarboxylate slump-retaining agents also have problems such as high sensitivity to raw material changes, too fast slump loss, and poor workability in actual applications. In addition, after decades of rapid urban construction development, the natural resources of concrete raw materials have been consumed greatly, and high-quality sand and stone resources are almost exhausted. It has become an inevitable trend to apply low-quality aggregates such as construction waste, manufactured sand, and natural sand and stone with high mud content to concrete. In the process of use, the high sensitivity of polycarboxylate slump-retaining agents often leads to problems such as fast concrete loss and pipe blockage, seriously affecting the pumping construction performance of concrete, and further affecting the mechanical properties and durability in the later stage. Therefore, how to reduce the sensitivity of polycarboxylate slump-retaining agents to raw material changes while improving the slump retention performance and workability has become an urgent technical problem to be solved. Summary of the Invention

[0005] One of the purposes of the present invention is to provide an ester-based polycarboxylate slump-retaining agent with low sensitivity to raw materials and good slump retention performance and workability.

[0006] Another purpose of the present invention is to provide a preparation method of a low-sensitivity ester-based polycarboxylate slump-retaining agent.

[0007] The third purpose of the present invention is to provide a low-sensitivity ester-based polycarboxylate slump-retaining agent prepared by the above method.

[0008] A fourth object of the present invention is to provide the application of the above low-sensitivity ester polycarboxylate slump retainer in the construction field.

[0009] The low-sensitivity ester polycarboxylate slump retainer provided by the present invention includes a polyester structural unit, a carboxylic acid structural unit, an esterification functional structural unit, and a carboxylic acid hydroxy ester structural unit; the esterification functional structural unit has at least one of the structures shown in formula (1-1), formula (1-2), and formula (1-3); the carboxylic acid hydroxy ester structural unit has the structures shown in formula (2-1) and formula (2-2);

[0010]

[0011]

[0012]

[0013]

[0014]

[0015] In formula (1-1) to formula (1-3), n is an integer from 1 to 100;

[0016] In formula (2-1), R 21 is H or an alkyl group with 1 to 5 carbon atoms, R 22 is an alkylene group with 0 to 4 carbon atoms, R 23 is an alkylene group with 1 to 5 carbon atoms;

[0017] In formula (2-2), R 21 is H or an alkyl group with 1 to 5 carbon atoms, R 23 is an alkylene group with 1 to 5 carbon atoms.

[0018] The preparation method of the low-sensitivity ester polycarboxylate slump retainer provided by the present invention includes:

[0019] S1. Esterify vinyl phthalic acid with polyethylene glycol. The vinyl phthalic acid has the structure shown in formula (5) to obtain an esterification functional monomer;

[0020] S2. Carry out a radical polymerization reaction on the esterification functional monomer, an unsaturated polyester monomer, an unsaturated carboxylic acid monomer, and a carboxylic acid hydroxy ester monomer. The carboxylic acid hydroxy ester monomer contains compound A shown in formula (6-1) and compound B shown in formula (6-2). The obtained polymerization reaction product is the low-sensitivity ester polycarboxylate slump retainer;

[0021]

[0022]

[0023]

[0024] In formula (6-1), R 21 is H or an alkyl group having 1 to 5 carbon atoms, and R 22 is an alkylene group having 0 to 4 carbon atoms, and R 23 is an alkylene group having 1 to 5 carbon atoms;

[0025] In formula (6-2), R 21 is H or an alkyl group having 1 to 5 carbon atoms, and R 23 is an alkylene group having 1 to 5 carbon atoms.

[0026] The present invention also provides a low-sensitivity ester polycarboxylate slump-retaining agent prepared by the above method.

[0027] The present invention also provides the application of the low-sensitivity ester polycarboxylate slump-retaining agent in the construction field.

[0028] The key of the present invention lies in carrying out free radical copolymerization of an esterification functional monomer and a carboxylic acid hydroxy ester monomer having a specific structure with an unsaturated polyester monomer and an unsaturated carboxylic acid monomer. The polycarboxylate slump-retaining agent obtained thereby can reduce the sensitivity of concrete, reduce the slump loss, improve the anti-clay performance, enhance the workability, reduce the sensitivity to raw material changes, facilitate the pumping of manufactured sand concrete, pumped concrete, etc., and effectively improve the concrete construction efficiency. Presumably, the reason may be that: the copolymerization of the above several monomers can not only effectively compensate for the early slump loss, improve the slump-retaining performance of concrete, and extend the slump loss time of concrete, but also make the side chains of the polycarboxylate slump-retaining agent molecule more extended, the steric hindrance effect more obvious, effectively reduce the viscosity of concrete, make it not easy to form intercalated adsorption with clay, improve the anti-clay performance, enhance the workability, and reduce the sensitivity to raw material changes. Specific Embodiments

[0029] The low-sensitivity ester polycarboxylate slump-retaining agent provided by the present invention includes a polyester structural unit, a carboxylic acid structural unit, an esterification functional structural unit, and a carboxylic acid hydroxy ester structural unit. The mass ratio of the polyester structural unit, the carboxylic acid structural unit, the esterification functional structural unit to the carboxylic acid hydroxy ester structural unit is 180:(5-10):(5-20):(10-30). Based on the content of the polyester structural unit being 180 parts by weight, the content of the carboxylic acid structural unit is 5-10 parts by weight, such as 5, 6, 7, 8, 9, 10 parts by weight or any value therebetween; the content of the esterification functional structural unit is 5-20 parts by weight, such as 5, 8, 10, 12, 15, 18, 20 parts by weight or any value therebetween; the content of the carboxylic acid hydroxy ester structural unit is 10-30 parts by weight, such as 10, 12, 15, 18, 20, 22, 25, 28, 30 parts by weight or any value therebetween.

[0030] In the present invention, the esterification functional structural unit has a structure shown in at least one of Formula (1-1), Formula (1-2) and Formula (1-3):

[0031]

[0032]

[0033]

[0034] In Formula (1-1) to Formula (1-3), n is an integer from 1 to 100, such as 1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or any value therebetween.

[0035] In the present invention, the carboxylic acid hydroxy ester structural unit has structures shown in Formula (2-1) and Formula (2-2).

[0036]

[0037]

[0038] In Formula (2-1), R 21 is H or an alkyl group having 1 to 5 carbon atoms, R 22 is an alkylene group having 0 to 4 carbon atoms, R 23 is an alkylene group having 1 to 5 carbon atoms. In Formula (2-2), R 21 is H or an alkyl group having 1 to 5 carbon atoms, R 23 is an alkylene group having 1 to 5 carbon atoms. Specific examples of the alkyl group having 1 to 5 carbon atoms include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl or neopentyl. Specific examples of the alkylene group having 0 to 5 carbon atoms include, but are not limited to: absent, methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene or neopentylene. Specific examples of the alkylene group having 0 to 4 carbon atoms include, but are not limited to: absent, methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene or tert-butylene.

[0039] In the present invention, the polyester structural unit preferably has a structure shown in Formula (3):

[0040]

[0041] In Formula (3), R 31 , R 32 and R 33 are each independently H, -COOH or an alkyl group having 1 to 5 carbon atoms, R 34is an alkylene group having 0 to 5 carbon atoms, R 35 is an alkyl group having 1 to 5 carbon atoms, and m is an integer from 1 to 100. Specific examples of the alkyl group having 1 to 5 carbon atoms include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl or neopentyl. Specific examples of the alkylene group having 0 to 5 carbon atoms include, but are not limited to: absent, methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene or neopentylene. m can be 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 or any value between them. The polyester structural unit is formed by polymerization of an unsaturated polyester monomer. Specific examples of the unsaturated polyester include, but are not limited to: at least one of methoxypolyethylene glycol methacrylate, methoxypolyethylene glycol acrylate and methoxypolyethylene glycol maleate.

[0042] In the present invention, the carboxylic acid structural unit preferably has the structure shown in formula (4):

[0043]

[0044] In formula (4), R 41 and R 42 are each independently H, an alkyl group having 1 to 5 carbon atoms or -R 43 -COOH and at least one of R 41 and R 42 is -R 43 -COOH, R 43 is an alkylene group having 0 to 5 carbon atoms; when R 41 and R 42 are both -R 43 -COOH, R 41 and R 42 can be bonded to form a ring; R 41 ` and R 42 ` are each independently H or an alkyl group having 1 to 5 carbon atoms. Among them, specific examples of the alkyl group having 1 to 5 carbon atoms include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl or neopentyl. Specific examples of the alkylene group having 1 to 5 carbon atoms include, but are not limited to: methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene or neopentylene. When R 41 and R 42 are both -R 43 -COOH, R 41 and R 42It can form a ring by bonding, and at this time, an acid anhydride is formed. The carboxylic acid structural unit is formed by the polymerization of unsaturated carboxylic acids. Among them, specific examples of the unsaturated carboxylic acid include, but are not limited to, at least one of acrylic acid, methacrylic acid, itaconic acid, and maleic anhydride.

[0045] In the present invention, the low-sensitivity ester polycarboxylate slump-retaining agent is preferably a random copolymer.

[0046] In the present invention, the number-average molecular weight of the low-sensitivity ester polycarboxylate slump-retaining agent is preferably 5000 to 80000, such as 5000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, or any value between them.

[0047] The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent provided by the present invention includes the following steps:

[0048] S1. Esterify vinyl phthalic acid and polyethylene glycol to obtain an esterification functional monomer;

[0049] S2. Carry out a radical polymerization reaction on the esterification functional monomer, an unsaturated polyester monomer, an unsaturated carboxylic acid monomer, and a carboxylic acid hydroxy ester monomer, and the obtained polymerization reaction product is the low-sensitivity ester polycarboxylate slump-retaining agent.

[0050] In the present invention, the mass ratio of the unsaturated polyester monomer, the unsaturated carboxylic acid monomer, the esterification functional monomer, and the carboxylic acid hydroxy ester monomer is preferably 180:(5 - 10):(5 - 20):(10 - 30). Based on the amount of the unsaturated polyester monomer being 180 parts by weight, the amount of the unsaturated carboxylic acid monomer is preferably 5 - 10 parts by weight, such as 5, 6, 7, 8, 9, 10 parts by weight, or any value between them; the content of the esterification functional monomer is preferably 5 - 20 parts by weight, such as 5, 8, 10, 12, 15, 18, 20 parts by weight, or any value between them; the content of the carboxylic acid hydroxy ester structural unit is preferably 10 - 30 parts by weight, such as 10, 12, 15, 18, 20, 22, 25, 28, 30 parts by weight, or any value between them.

[0051] In the preparation process of the above esterification functional monomer, the molar ratio of vinyl phthalic acid to polyethylene glycol is preferably (2 - 4):1, such as 2:1, 2.5:1, 3:1, 3.5:1, 5:1, or any value between them.

[0052] In the preparation process of the above esterification functional monomer, the vinyl phthalic acid has the structure shown in formula (5), and its specific examples include, but are not limited to, 4-vinyl-1,2-phthalic acid.

[0053]

[0054] In the preparation process of the above esterification functional monomer, specific examples of the polyethylene glycol include but are not limited to at least one of PEG-200, PEG-400, PEG-600, PEG-800, and PEG-1000.

[0055] In the preparation process of the above esterification functional monomer, the conditions of the esterification reaction preferably include a temperature of 80°C to 100°C, such as 80°C, 82°C, 85°C, 88°C, 90°C, 92°C, 95°C, 98°C, 100°C, or any value therebetween; and a time of 1 to 5 h, such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, or any value therebetween.

[0056] In the preparation process of the above esterification functional monomer, the esterification reaction is preferably carried out in the presence of a catalyst and an inhibitor. Among them, the catalyst can be various existing substances capable of catalyzing the esterification reaction, and specific examples thereof include but are not limited to at least one of concentrated sulfuric acid, p-toluenesulfonic acid, stannous oxide, and dibutyltin oxide; the dosage of the catalyst preferably accounts for 1% to 3% of the total mass of vinyl phthalic acid and polyethylene glycol, such as 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, or any value therebetween. Specific examples of the inhibitor include but are not limited to at least one of p-methoxyphenol, hydroquinone, and phenothiazine. The dosage of the inhibitor preferably accounts for 0.1% to 2% of the total mass of vinyl phthalic acid and polyethylene glycol, such as 1%, 1.2%, 1.5%, 1.8%, 2%, or any value therebetween.

[0057] In the present invention, the carboxylic acid hydroxy ester monomer contains compound A represented by formula (6-1) and compound B represented by formula (6-2). Among them, the mass ratio of compound A to compound B in the carboxylic acid hydroxy ester monomer is preferably 1:(2 to 4), such as 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.5, 1:3.8, 1:4, or any value therebetween. Using compound A and compound B in combination according to this preferred ratio has the advantage of strong slump retention ability for a long time.

[0058]

[0059] In formula (6-1), R 21 is H or an alkyl group having 1 to 5 carbon atoms, R 22 is an alkylene group having 0 to 4 carbon atoms, R 23 is an alkylene group having 1 to 5 carbon atoms. In formula (6-2), R 21 is H or an alkyl group having 1 to 5 carbon atoms, R 23is an alkylene group having 1 to 5 carbon atoms. Specific examples of the alkyl group having 1 to 5 carbon atoms include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl or neopentyl. Specific examples of the alkylene group having 0 to 4 carbon atoms include, but are not limited to: absent, methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene or tert-butylene. Specific examples of the alkylene group having 1 to 5 carbon atoms include, but are not limited to: methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene or neopentylene.

[0060] In the present invention, the unsaturated polyester monomer preferably has the structure shown in formula (7):

[0061]

[0062] In formula (7), R 31 , R 32 and R 33 are each independently H, -COOH or an alkyl group having 1 to 5 carbon atoms, R 34 is an alkylene group having 0 to 5 carbon atoms, R 35 is an alkyl group having 1 to 5 carbon atoms, and m is an integer from 1 to 100. Specific examples of the alkyl group having 1 to 5 carbon atoms include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl or neopentyl. Specific examples of the alkylene group having 0 to 5 carbon atoms include, but are not limited to: absent, methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene or neopentylene. m can be 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 or any value between them. Specific examples of the unsaturated polyester monomer include, but are not limited to: at least one of methoxypolyethylene glycol methacrylate, methoxypolyethylene glycol acrylate and methoxypolyethylene glycol maleate.

[0063] In the present invention, the unsaturated carboxylic acid monomer preferably has the structure shown in formula (8):

[0064]

[0065] In formula (8), R 41 and R 42 are each independently H, an alkyl group having 1 to 5 carbon atoms or -R 43 -COOH and at least one of R 41 and R 42 is -R43 -COOH, R 43 is absent or is a C1-C5 alkylene group; when R 41 and R 42 are both -R 43 -COOH, R 41 and R 42 can form a ring by bonding; R 41 ` and R 42 ` are each independently H or a C1-C5 alkyl group. Specific examples of the C1-C5 alkyl group include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl or neopentyl. Specific examples of the C1-C5 alkylene group include, but are not limited to: methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene or neopentylene. When R 41 and R 42 are both -R 43 -COOH, R 41 and R 42 can form a ring by bonding, and an acid anhydride is formed at this time. Considering the availability of raw materials, the unsaturated carboxylic acid is particularly preferably at least one selected from acrylic acid, methacrylic acid, itaconic acid and maleic anhydride.

[0066] The present invention does not particularly limit the type of initiator used in the free radical polymerization reaction, and it can be at least one selected from azo initiators, peroxide initiators, and redox initiators. Among them, specific examples of the azo initiator include, but are not limited to: at least one of dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylpropionamidine) dihydrochloride, azodicarbonamide, 2,2'-azobis(2-isopropylimidazoline) hydrochloride, 2-cyano-2-propylazoformamide, 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(isopropyl)imidazoline, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2-methylhexanenitrile). Specific examples of the peroxide initiator include, but are not limited to: at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, benzoyl peroxide, and tert-butyl peroxybenzoate. The redox initiator includes an oxidizing agent and a reducing agent, and specific examples thereof include, but are not limited to: at least one of sulfate-sulfite, persulfate-thiourea, persulfate-organic salt, and ammonium persulfate-fatty amine. Among them, the sulfate-sulfite can be at least one selected from sodium sulfate-sodium sulfite, potassium sulfate-potassium sulfite, and ammonium sulfate-ammonium sulfite. The persulfate-thiourea can be at least one selected from sodium persulfate-thiourea, potassium persulfate-thiourea, and ammonium persulfate-thiourea. The persulfate-organic salt can be at least one selected from sodium persulfate-potassium acetate, potassium persulfate-potassium acetate, and ammonium persulfate-ammonium acetate. The ammonium persulfate-fatty amine can be ammonium persulfate-N,N-tetramethylethylenediamine and / or ammonium persulfate-diethylamine. The free radical polymerization reaction preferably uses a redox initiator.

[0067] In a preferred embodiment, the mode of the free radical polymerization reaction includes:

[0068] S1`: Dissolve the unsaturated polyester monomer and the oxidizing agent in water to obtain a substrate;

[0069] S2`: Drop the A solution and the B solution into the substrate respectively for a polymerization reaction. The A solution is a reducing agent solution, and the B solution is a mixed solution of an esterification functional monomer, an unsaturated carboxylic acid monomer, a carboxylic acid hydroxy ester monomer, and a molecular weight regulator. The product obtained after the reaction is a low-sensitivity ester polycarboxylate slump retaining agent.

[0070] In the preparation process of the above-mentioned low-sensitivity ester polycarboxylate slump-retaining agent, specific examples of the oxidant include, but are not limited to, at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, cumene hydroperoxide, benzoyl peroxide, and tert-butyl hydroperoxide, preferably a mixture of two or more. Specific examples of the reducing agent include, but are not limited to, at least one of ascorbic acid, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 1,1'-azobis(cyclohexanecarbonitrile), sodium bisulfite, sodium sulfite, sodium metabisulfite, sodium formaldehyde sulfoxylate, ferrous sulfate heptahydrate, sodium hypophosphite, sodium phosphite, and ammonium ferrous sulfate, preferably a mixture of two or more. The dosage of the oxidant is preferably 1% to 5% of the total mass of the unsaturated polyester monomer, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any value between them. The dosage of the reducing agent is preferably 0.1% to 2% of the total mass of the unsaturated polyester monomer, such as 0.1%, 0.3%, 0.5%, 1%, 1.5%, 2% or any value between them.

[0071] In the preparation process of the above-mentioned low-sensitivity ester polycarboxylate slump-retaining agent, the molecular weight regulator is preferably a thiol compound, more preferably selected from one of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol. In addition, the dosage of the molecular weight regulator is preferably 1% to 5% of the total mass of the unsaturated polyester monomer, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any value between them.

[0072] In the preparation process of the above-mentioned low-sensitivity ester polycarboxylate slump-retaining agent, the A solution and the B solution are respectively dropped into the substrate for free radical polymerization reaction. Among them, the dropping time of the A solution is preferably 120 to 180 min, such as 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min or any value between them. The dropping time of the B solution is preferably 120 to 180 min, such as 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min or any value between them.

[0073] In the preparation process of the above-mentioned low-sensitivity ester polycarboxylate slump-retaining agent, the conditions of the free radical polymerization reaction preferably include a temperature of 15 to 40 °C, such as 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C or any value between them; the reaction time after the solution is dropped is 20 to 60 min, such as 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min or any value between them.

[0074] The present invention also provides a low-sensitivity ester polycarboxylate slump-retaining agent prepared by the above method.

[0075] The present invention also provides an application of the above low-sensitivity ester polycarboxylate slump-retaining agent in the construction field.

[0076] The present invention will be described in detail below through examples.

[0077] In the following examples and comparative examples, the parts of raw materials are all by weight.

[0078] In the following examples, the dosages of each raw material are shown in Table 1.

[0079] In the following comparative examples, the dosages of each raw material are shown in Table 2.

[0080] Example 1

[0081] S1. Esterification reaction: Mix 4-vinyl-1,2-benzenedicarboxylic acid and PEG-200 in a molar ratio of 2:1, add 3% p-toluenesulfonic acid and 2% p-hydroxyanisole, and under nitrogen protection, carry out an esterification reaction at 90 °C for 3 h to obtain an esterification functional monomer D1;

[0082] S2. Polymerization reaction: By mass, add 180 parts of methoxypolyethylene glycol methacrylate (Mn is 3000) and 100 parts of water to the reaction kettle. After stirring and dispersing evenly, add 1 part of hydrogen peroxide at one time and react at 25 °C for 10 min, and then dropwise add solution A and solution B. Among them, solution A is 10 parts of a 10% sodium hypophosphite solution by mass. Solution B is a mixed solution composed of 20 parts of esterification functional monomer D1, 5 parts of maleic acid, 5 parts of 2-hydroxyethyl 4-vinylbenzoate (compound A), 10 parts of hydroxybutyl methacrylate (compound B), and 2 parts of mercaptoacetic acid. The dropping time of solution A is 120 min, the dropping time of solution B is 120 min, and after the dropping is completed, continue to react for 30 min to obtain the low-sensitivity ester polycarboxylate slump-retaining agent BT-1.

[0083] Example 2

[0084] S1. Esterification reaction: Mix 4-vinyl-1,2-benzenedicarboxylic acid and PEG-400 in a molar ratio of 3:1, add 2% stannous oxide and 2% hydroquinone, and under nitrogen protection, carry out an esterification reaction at 80 °C for 4 h to obtain an esterification functional monomer D2;

[0085] S2. Polymerization reaction: 180 parts by mass of methoxypolyethylene glycol acrylate (Mn = 2600) and 100 parts of water were added to a reaction kettle. After being stirred and dispersed evenly, 2 parts of ammonium persulfate were added at one time. After reacting at 30 °C for 10 min, solution A and solution B were added dropwise. Among them, solution A was 10 parts of an L-ascorbic acid solution with a mass concentration of 5%. Solution B was a mixed solution composed of 10 parts of esterification functional monomer D2, 7 parts of itaconic acid, 3 parts of hydroxypropyl 4-propenylbenzoate (compound A), 7 parts of hydroxypropyl methacrylate (compound B), and 4 parts of mercaptoethanol. The dropping time of solution A was 150 min, and the dropping time of solution B was 150 min. After the dropping was completed, the reaction was continued for 30 min to obtain the low-sensitivity ester polycarboxylate slump retainer BT-2.

[0086] Example 3

[0087] S1. Esterification reaction: 4-vinyl-1,2-benzenedicarboxylic acid and PEG-600 were mixed at a molar ratio of 4:1, 2% of dibutyltin oxide and 0.2% of phenothiazine were added, and under nitrogen protection, the esterification reaction was carried out at 100 °C for 2 h to obtain the esterification functional monomer D3;

[0088] S2. Polymerization reaction: 180 parts by mass of methoxypolyethylene glycol maleate (Mn = 2700) and 100 parts of water were added to a reaction kettle. After being stirred and dispersed evenly, 3 parts of hydrogen peroxide were added at one time. After reacting at 20 °C for 10 min, solution A and solution B were added dropwise. Among them, solution A was 20 parts of a sodium hypophosphite solution with a mass concentration of 10%. Solution B was a mixed solution composed of 15 parts of esterification functional monomer D3, 6 parts of acrylic acid, 4 parts of hydroxyethyl 4-methylpropenylbenzoate (compound A), 16 parts of hydroxypropyl acrylate (compound B), and 5 parts of sulfonated mercaptopropionic acid. The dropping time of solution A was 180 min, and the dropping time of solution B was 180 min. After the dropping was completed, the reaction was continued for 30 min to obtain the low-sensitivity ester polycarboxylate slump retainer BT-3.

[0089] Example 4

[0090] S1. Esterification reaction: 4-vinyl-1,2-benzenedicarboxylic acid and PEG-400 were mixed at a molar ratio of 3:1, 1% of concentrated sulfuric acid and 0.8% of phenothiazine were added, and under nitrogen protection, the esterification reaction was carried out at 90 °C for 3 h to obtain the esterification functional monomer D4;

[0091] S2. Polymerization reaction: 180 parts by mass of methoxypolyethylene glycol methacrylate (Mn = 2200) and 100 parts of water were added to a reaction kettle. After being stirred and dispersed evenly, 5 parts of ammonium persulfate were added at one time. The reaction was carried out at 30 °C for 10 min, and then solution A and solution B were added dropwise. Among them, solution A was 10 parts of a 1% L-ascorbic acid solution by mass concentration. Solution B was a mixed solution composed of 5 parts of esterification functional monomer D4, 10 parts of methacrylic acid, 7 parts of 4-butenyl-hydroxybutyl benzoate (compound A), 21 parts of hydroxyethyl acrylate (compound B), and 1 part of mercaptopropionic acid. The dropping time of solution A was 180 min, and the dropping time of solution B was 160 min. After the dropping was completed, the reaction was continued for 30 min to obtain the low-sensitivity ester polycarboxylate slump retainer BT-4.

[0092] Comparative Example 1

[0093] The low-sensitivity ester polycarboxylate slump retainer was prepared according to the method of Example 1, except that the esterification functional monomer was not prepared and not added, and the other conditions were the same as those in Example 1. The specific steps were as follows:

[0094] 180 parts by mass of methoxypolyethylene glycol methacrylate and 100 parts of water were added to a reaction kettle. After being stirred and dispersed evenly, 1 part of hydrogen peroxide was added at one time. The reaction was carried out at 25 °C for 10 min, and then solution A and solution B were added dropwise. Among them, solution A was 10 parts of a 10% sodium hypophosphite solution by mass concentration. Solution B was a mixed solution composed of 5 parts of maleic acid, 5 parts of 4-vinyl-hydroxyethyl benzoate (compound A), 10 parts of hydroxybutyl methacrylate (compound B), and 2 parts of mercaptoacetic acid. The dropping time of solution A was 120 min, and the dropping time of solution B was 120 min. After the dropping was completed, the reaction was continued for 30 min to obtain the low-sensitivity ester polycarboxylate slump retainer DBT-1.

[0095] Comparative Example 2

[0096] The low-sensitivity ester polycarboxylate slump retainer was prepared according to the method of Example 1, except that 4-vinyl-hydroxyethyl benzoate (compound A) was replaced with the same weight parts of hydroxybutyl methacrylate (compound B), and the other conditions were the same as those in Example 1. The specific steps were as follows:

[0097] S1. Esterification reaction: 4-vinyl-1,2-benzenedicarboxylic acid and PEG-200 were mixed at a molar ratio of 2:1, 3% p-toluenesulfonic acid and 2% p-hydroxyanisole were added, and under nitrogen protection, the esterification reaction was carried out at 90 °C for 3 h to obtain the esterification functional monomer D1;

[0098] S2. Polymerization reaction: Add 180 parts of methoxypolyethylene glycol methacrylate and 100 parts of water to the reaction kettle by mass. After stirring and dispersing evenly, add 1 part of hydrogen peroxide at one time, react at 25 °C for 10 min, and then dropwise add Solution A and Solution B. Among them, Solution A is 10 parts of a sodium hypophosphite solution with a mass concentration of 10%. Solution B is a mixed solution composed of 20 parts of esterification functional monomer D1, 5 parts of maleic acid, 15 parts of hydroxybutyl methacrylate (Compound B), and 2 parts of mercaptoacetic acid. The dropping time of Solution A is 120 min, the dropping time of Solution B is 120 min, and after the dropping is completed, continue to react for 30 min to obtain the low-sensitivity ester polycarboxylate slump retaining agent DBT-2.

[0099] Comparative Example 3

[0100] Prepare the low-sensitivity ester polycarboxylate slump retaining agent according to the method of Example 1. The difference is that in the preparation process of the esterification functional monomer, 4-vinyl-1,2-benzenedicarboxylic acid is replaced with acrylic acid of the same molar amount, and the other conditions are the same as those in Example 1. The specific steps are as follows:

[0101] S1. Esterification reaction: Mix acrylic acid and PEG-200 in a molar ratio of 2:1, add 3% p-toluenesulfonic acid and 2% p-hydroxyanisole, and carry out an esterification reaction at 90 °C for 3 h under nitrogen protection to obtain the esterification functional monomer D6;

[0102] S2. Polymerization reaction: Add 180 parts of methoxypolyethylene glycol methacrylate and 100 parts of water to the reaction kettle by mass. After stirring and dispersing evenly, add 1 part of hydrogen peroxide at one time, react at 25 °C for 10 min, and then dropwise add Solution A and Solution B. Among them, Solution A is 10 parts of a sodium hypophosphite solution with a mass concentration of 10%. Solution B is a mixed solution composed of 20 parts of esterification functional monomer D6, 5 parts of maleic acid, 5 parts of 2-hydroxyethyl 4-vinylbenzoate (Compound A), 10 parts of hydroxybutyl methacrylate (Compound B), and 2 parts of mercaptoacetic acid. The dropping time of Solution A is 120 min, the dropping time of Solution B is 120 min, and after the dropping is completed, continue to react for 30 min to obtain the low-sensitivity ester polycarboxylate slump retaining agent DBT-3.

[0103] Comparative Example 4

[0104] Prepare the low-sensitivity ester polycarboxylate slump retaining agent according to the method of Example 1. The difference is that 2-hydroxyethyl 4-vinylbenzoate (Compound A) is replaced with poly(ethylene glycol) diacrylate (number average molecular weight of 1308) of the same weight part, and the other conditions are the same as those in Example 1. The specific steps are as follows:

[0105] S1. Esterification reaction: Mix 4-vinyl-1,2-benzenedicarboxylic acid with PEG-200 at a molar ratio of 2:1, add 3% p-toluenesulfonic acid and 2% p-hydroxyanisole, and carry out the esterification reaction at 90 °C for 3 h under nitrogen protection to obtain the esterification functional monomer D1;

[0106] S2. Polymerization reaction: By mass, add 180 parts of methoxypolyethylene glycol methacrylate and 100 parts of water to the reaction kettle. After stirring and dispersing evenly, add 1 part of hydrogen peroxide at one time, react at 25 °C for 10 min, and then dropwise add solution A and solution B. Among them, solution A is 10 parts of a 10% sodium hypophosphite solution by mass concentration. Solution B is a mixed solution composed of 20 parts of the esterification functional monomer D1, 5 parts of maleic acid, 5 parts of polyethylene glycol diacrylate, 10 parts of hydroxybutyl methacrylate (compound B), and 2 parts of mercaptoacetic acid. The dropping time of solution A is 120 min, and the dropping time of solution B is 120 min. After the dropping is completed, continue to react for 30 min to obtain the low-sensitivity ester polycarboxylate slump retainer DBT-4.

[0107] Comparative Example 5

[0108] Prepare the low-sensitivity ester polycarboxylate slump retainer according to the method of Example 1. The difference is that in the preparation process of the esterification functional monomer, PEG-200 is replaced with methoxypolyethylene glycol MPEG-200 with the same molar amount, and the other conditions are the same as those in Example 1. The specific steps are as follows:

[0109] S1. Esterification reaction: Mix 4-vinyl-1,2-benzenedicarboxylic acid with MPEG-200 at a molar ratio of 2:1, add 3% p-toluenesulfonic acid and 2% p-hydroxyanisole, and carry out the esterification reaction at 90 °C for 3 h under nitrogen protection to obtain the esterification functional monomer D7;

[0110] S2. Polymerization reaction: By mass, add 180 parts of methoxypolyethylene glycol methacrylate and 100 parts of water to the reaction kettle. After stirring and dispersing evenly, add 1 part of hydrogen peroxide at one time, react at 25 °C for 10 min, and then dropwise add solution A and solution B. Among them, solution A is 10 parts of a 10% sodium hypophosphite solution by mass concentration. Solution B is a mixed solution composed of 20 parts of the esterification functional monomer D7, 5 parts of maleic acid, 5 parts of hydroxyethyl 4-vinylbenzoate (compound A), 10 parts of hydroxybutyl methacrylate (compound B), and 2 parts of mercaptoacetic acid. The dropping time of solution A is 120 min, and the dropping time of solution B is 120 min. After the dropping is completed, continue to react for 30 min to obtain the low-sensitivity ester polycarboxylate slump retainer DBT-5.

[0111] Table 1 Formulation of Examples

[0112]

[0113] Table 2 Formulation of Comparative Example

[0114]

[0115]

[0116] Test Example 1

[0117] (1) According to GB / T 8077-2012 "Test Methods for Homogeneity of Concrete Admixtures", the net paste fluidity of the polycarboxylate slump-retaining agents obtained from the above examples and comparative examples was tested under different dosages and water consumption. Among them, during the test of different dosages, the cement dosage was 300 g and the water dosage was 87 g, and the results are shown in Table 3. During the test of different water consumption, the cement dosage was 300 g and the slump-retaining agent dosage was 2.0%, and the results are shown in Table 4.

[0118] Table 3

[0119]

[0120]

[0121] Table 4

[0122]

[0123]

[0124] It can be seen from the test results in Table 3 and Table 4 that the polycarboxylate slump-retaining agent provided by the present invention is less sensitive in terms of dosage and water consumption.

[0125] Test Example 2

[0126] 60 g of the low-sensitivity ester polycarboxylate slump-retaining agents obtained from the above examples and comparative examples were respectively mixed evenly with 140 g of water-reducing agent PCE (purchased from Kezhijie New Materials Group Co., Ltd., brand name Point-7408) and 800 g of water to obtain test samples. The test samples were made of Conch Cement, and according to GB 8076-2008 "Concrete Admixtures", the initial slump and spread of the concrete, the slump and spread over time, and the concrete state were measured. The concrete mix ratio was: cement 230 kg / m 3 , fly ash (Grade II) 90 kg / m 3 , machine-made sand 850 kg / m 3 (mud content is 8%), stone (5 - 31.5) mm) 1050 kg / m 3 , and the initial spread was controlled within 550 ± 10 mm, and the obtained results are shown in Table 5.

[0127] Table 5

[0128]

[0129] As can be seen from the test results in Table 5, the low-sensitivity ester polycarboxylate slump-retaining agent provided by the present invention has a low dosage and a small slump loss over time. This polycarboxylate slump-retaining agent can improve the slump-retaining performance of concrete, reduce the slump loss during pumping, and has advantages such as good workability, good wrapping property, fast flow rate, and good anti-clay effect. It can improve the pumping efficiency of concrete, improve the workability of concrete at the same time, and avoid problems such as pipe blockage caused by large late-stage loss of concrete.

[0130] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention.

Claims

1. A low-sensitivity ester polycarboxylate slump-retaining agent, characterized in that, The low-sensitivity ester polycarboxylate slump retainer includes a polyester structural unit, a carboxylic acid structural unit, an esterification functional structural unit, and a carboxylic acid hydroxy ester structural unit; the esterification functional structural unit has a structure shown in at least one of Formula (1-1), Formula (1-2), and Formula (1-3); the carboxylic acid hydroxy ester structural unit has structures shown in Formula (2-1) and Formula (2-2); In Formula (1-1) to Formula (1-3), n is an integer from 1 to 100; In formula (2-1), R 21 is H or an alkyl group having 1 to 5 carbon atoms, R 22 is an alkylene group having 0 to 4 carbon atoms, R 23 is an alkylene group having 1 to 5 carbon atoms; In formula (2-2), R 21 is H or an alkyl group having 1 to 5 carbon atoms, and R 23 is an alkylene group having 1 to 5 carbon atoms.

2. The low-sensitivity ester polycarboxylate slump-retaining agent according to claim 1, characterized in that, The mass ratio of the polyester structural unit, the carboxylic acid structural unit, the esterification functional structural unit, and the carboxylic acid hydroxy ester structural unit is 180:(5-10):(5-20):(10-30).

3. The low-sensitivity ester polycarboxylate slump-retaining agent according to claim 1 or 2, characterized in that, The polyester structural unit has a structure shown in Formula (3): In formula (3), R 31 , R 32 and R 33 are each independently H, -COOH or an alkyl group having 1 to 5 carbon atoms, R 34 is an alkylene group having 0 to 5 carbon atoms, R 35 is an alkyl group having 1 to 5 carbon atoms, and m is an integer from 1 to 100.

4. The low-sensitivity ester polycarboxylate slump-retaining agent according to claim 1 or 2, characterized in that, The carboxylic acid structural unit has a structure shown in Formula (4): In formula (4), R 41 and R 42 are each independently H, an alkyl group having 1 to 5 carbon atoms, or -R 43 -COOH, and at least one of R 41 and R 42 is -R 43 -COOH, R 43 is an alkylene group having 0 to 5 carbon atoms; when both R 41 and R 42 are -R 43 -COOH, R 41 and R 42 can be bonded to form a ring; R 41 ` and R 42 ` are each independently H or an alkyl group having 1 to 5 carbon atoms.

5. A preparation method of a low-sensitivity ester polycarboxylate slump-retaining agent, characterized in that, This method includes: S1. Esterify vinyl phthalic acid with polyethylene glycol. The vinyl phthalic acid has a structure shown in Formula (5) to obtain an esterification functional monomer; S2. Carry out a radical polymerization reaction on the esterification functional monomer, an unsaturated polyester monomer, an unsaturated carboxylic acid monomer, and a carboxylic acid hydroxy ester monomer. The carboxylic acid hydroxy ester monomer contains Compound A shown in Formula (6-1) and Compound B shown in Formula (6-2). The obtained polymerization reaction product is the low-sensitivity ester polycarboxylate slump retainer; In formula (6-1), R 21 is H or an alkyl group having 1 to 5 carbon atoms, R 22 is an alkylene group having 0 to 4 carbon atoms, R 23 is an alkylene group having 1 to 5 carbon atoms; In formula (6-2), R 21 is H or an alkyl group having 1 to 5 carbon atoms, and R 23 is an alkylene group having 1 to 5 carbon atoms.

6. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 5, characterized in that, The ways of the radical polymerization reaction include: S1`. Dissolve the unsaturated polyester monomer and an oxidant in water to obtain a substrate; S2`. Drop the A solution and the B solution into the substrate respectively for polymerization reaction. The A solution is a reducing agent solution, and the B solution is a mixed solution of an esterification functional monomer, an unsaturated carboxylic acid monomer, a carboxylic acid hydroxy ester monomer, and a molecular weight regulator. The product obtained after the reaction is the low-sensitivity ester polycarboxylate slump retainer.

7. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 5, characterized in that, The mass ratio of the unsaturated polyester monomer, the unsaturated carboxylic acid monomer, the esterification functional monomer, and the carboxylic acid hydroxy ester monomer is 180:(5-10):(5-20):(10-30).

8. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 5, characterized in that, In the preparation process of the esterification functional monomer, the molar ratio of vinyl phthalic acid to polyethylene glycol is (2-4):

1.

9. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 5, characterized in that, The vinyl phthalic acid is 4-vinyl-1,2-phthalic acid.

10. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 5, characterized in that, The polyethylene glycol is selected from at least one of PEG-200, PEG-400, PEG-600, PEG-800, and PEG-1000.

11. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 5, wherein, The conditions of the esterification reaction include a temperature of 80°C to 100°C and a time of 1 to 5 h.

12. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 5, wherein, The esterification reaction is carried out in the presence of a catalyst and an inhibitor.

13. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 12, wherein, The catalyst is selected from at least one of concentrated sulfuric acid, p-toluenesulfonic acid, stannous oxide, and dibutyltin oxide.

14. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 12, wherein, The dosage of the catalyst accounts for 1% to 3% of the total mass of vinyl phthalic acid and polyethylene glycol.

15. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 12, wherein, The inhibitor is selected from at least one of p-methoxyphenol, hydroquinone, and phenothiazine.

16. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 12, wherein, The dosage of the inhibitor accounts for 0.1% to 2% of the total mass of vinyl phthalic acid and polyethylene glycol.

17. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 5, wherein, The unsaturated polyester monomer has a structure shown in Formula (7): In formula (7), R 31 , R 32 and R 33 are each independently H, -COOH or an alkyl group having 1 to 5 carbon atoms, R 34 is an alkylene group having 0 to 5 carbon atoms, R 35 is an alkyl group having 1 to 5 carbon atoms, and m is an integer from 1 to 100.

18. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 17, wherein, The unsaturated polyester monomer is selected from at least one of methoxypolyethylene glycol methacrylate, methoxypolyethylene glycol acrylate, and methoxypolyethylene glycol maleate.

19. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 5, wherein, The unsaturated carboxylic acid monomer has the structure shown in formula (8): In formula (8), R 41 and R 42 are each independently H, an alkyl group having 1 to 5 carbon atoms, or -R 43 -COOH, and at least one of R 41 and R 42 is -R 43 -COOH, R 43 is an alkylene group having 0 to 5 carbon atoms; when both R 41 and R 42 are -R 43 -COOH, R 41 and R 42 can form a ring by bonding; R 41 ` and R 42 ` are each independently H or an alkyl group having 1 to 5 carbon atoms.

20. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 19, wherein, The unsaturated carboxylic acid monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, and maleic acid.

21. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 5, wherein, The mass ratio of compound A to compound B in the carboxylic acid hydroxy ester monomer is 1:(2 - 4).

22. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 6, wherein, The oxidant is selected from at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, cumene hydroperoxide, benzoyl peroxide, and tert-butyl hydroperoxide.

23. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 6, wherein, The reducing agent is selected from at least one of ascorbic acid, sodium bisulfite, sodium sulfite, sodium metabisulfite, sodium formaldehyde sulfoxylate, ferrous sulfate heptahydrate, sodium hypophosphite, sodium phosphite, and ammonium ferrous sulfate.

24. The preparation method of the low-sensitivity ester-based polycarboxylate slump-retaining agent according to claim 6, wherein, The molecular weight regulator is a thiol compound.

25. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 24, wherein, The molecular weight regulator is selected from at least one of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol.

26. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 6, wherein, The dosage of the oxidant is 1% - 5% of the total mass of the unsaturated polyester monomer.

27. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 6, wherein, The dosage of the reducing agent is 0.1% - 2% of the total mass of the unsaturated polyester monomer.

28. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 6, wherein, The dosage of the molecular weight regulator is 1% - 5% of the total mass of the unsaturated polyester monomer.

29. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 6, wherein, The dropping time of the A solution is 120 - 180 min.

30. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 6, wherein, The dropping time of the B solution is 120 - 180 min.

31. The preparation method of the low-sensitivity ester polycarboxylate slump-retaining agent according to claim 6, wherein, The conditions of the polymerization reaction include an initial dropping temperature of 15 - 35 °C and a reaction time of 20 - 60 min after the solution is dropped completely.

32. The low-sensitivity ester polycarboxylate slump-retaining agent prepared by the method according to any one of claims 5 to 31.

33. The application of the low-sensitivity ester polycarboxylate slump-retaining agent according to any one of claims 1 to 4 and 32 in the construction field.

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