A high-slump-retention polycarboxylate water-reducing agent and its preparation method and use

Abstract

The invention discloses a high-slump-retention polycarboxylate water-reducing agent, a preparation method thereof, and uses thereof, and relates to the technical field of polycarboxylate water-reducing agents. A polyether monomer, a carboxylic acid monomer, and an organosilicon monomer are subjected to a free radical copolymerization reaction under the action of an initiator and a chain transfer agent to obtain the polycarboxylate water-reducing agent. The polycarboxylate water-reducing agent of the invention has excellent water-reducing and slump-retention properties under low dosage conditions, can reduce the amount of water used in concrete mixing, achieve uniform dispersion of cement particles in concrete, improve the fluidity and filling properties of concrete, make concrete easier to construct and form, and enhance the strength and durability of concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of polycarboxylate water reducers, and in particular to a high-slump-retention polycarboxylate water reducer, a preparation method thereof, and uses thereof. Background Art

[0002] As a high-performance water-reducing agent, polycarboxylate superplasticizer plays a vital role in cement concrete engineering and is widely used in projects such as highways, bridges, dams, tunnels, and high-rise buildings. Polycarboxylate superplasticizers are non-flammable and non-explosive, making them safe to transport. Based on their backbone structure, polycarboxylate superplasticizers can be divided into two categories: one based on acrylic acid or methacrylic acid as the main chain, grafted with polyethers of varying side chain lengths; the other based on maleic anhydride as the main chain, grafted with polyethers of varying side chain lengths.

[0003] The transportation of concrete from the mixing plant to the construction site inevitably reduces its fluidity, accelerating slump loss. Furthermore, concrete mixed with polycarboxylate superplasticizers, due to the low mixing water requirement, can also experience accelerated slump loss and increased viscosity, impacting proper construction and making it difficult to guarantee quality. While the addition of retarders can improve concrete's slump retention, it does not fundamentally address the slump loss issue. Furthermore, compatibility issues between retarders and superplasticizers, as well as between retarders and cement, can affect concrete performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a high-slump-retaining polycarboxylate water-reducing agent. The obtained polycarboxylate water-reducing agent can be used as a cement dispersant, exhibits excellent water-reducing and slump-retaining properties, and improves the construction effect and quality of concrete.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0006] One of the purposes of the present invention is to provide a method for preparing a polycarboxylate water reducer, wherein a polyether monomer, a carboxylic acid monomer and a silicone monomer are subjected to a free radical copolymerization reaction under the action of an initiator and a chain transfer agent to obtain the polycarboxylate water reducer.

[0007] Furthermore, the organosilicon monomer is obtained by a substitution reaction between allyl (chloromethyl) dimethyl silane and 2-(methylsulfonyl) ethylamine in the presence of an acid-binding agent. The acid-binding agent includes, but is not limited to, at least one of potassium carbonate, sodium carbonate, sodium hydroxide, sodium acetate, triethylamine, pyridine, and N,N-diisopropylethylamine. The molar ratio of allyl (chloromethyl) dimethyl silane, 2-(methylsulfonyl) ethylamine, and acid-binding agent is 1:(1-1.1):(1-1.1). The acid-binding agent accelerates the reaction rate by neutralizing the hydrogen chloride generated by the substitution reaction. A moderate excess of 2-(methylsulfonyl) ethylamine and acid-binding agent can increase the conversion rate of allyl (chloromethyl) dimethyl silane and the yield of the organosilicon monomer.

[0008] Furthermore, the polyether monomer includes but is not limited to at least one of allyl alcohol polyoxyethylene ether, isopentenol polyoxyethylene ether, isobutylenol polyoxyethylene ether, and methylallyl alcohol polyoxyethylene ether.

[0009] Furthermore, the carboxylic acid monomer includes but is not limited to at least one of acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.

[0010] Furthermore, the initiator is a redox initiator, comprising an oxidizing agent and a reducing agent. The oxidizing agent includes, but is not limited to, at least one of hydrogen peroxide, potassium persulfate, ammonium persulfate, and sodium persulfate. The reducing agent includes, but is not limited to, at least one of L-ascorbic acid, sodium sulfite, sodium bisulfite, ferrous sulfate, and ferrous chloride. Redox initiators generate free radicals through redox reactions, thereby initiating polymerization reactions.

[0011] Furthermore, the chain transfer agent includes but is not limited to at least one of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol. The main function of the chain transfer agent is to regulate the activity and stability of free radicals, thereby controlling the molecular weight and molecular weight distribution of the polymer.

[0012] Furthermore, the mass ratio of the polyether monomer, carboxylic acid monomer, and silicone monomer is 1: (3-4): (0.2-0.5). The polycarboxylic acid water-reducing agent with the structure is synthesized by mainly using the carboxylic acid monomer and adding appropriate amounts of the polyether monomer and silicone monomer.

[0013] Furthermore, the amount of the initiator used is 0.1-1% of the total weight of the monomers. If the amount of initiator used is too little, the polymerization reaction will be slow or incomplete; if the amount of initiator used is too much, the polymerization reaction will be too fast, which may result in a lower molecular weight of the polymer and a wider molecular weight distribution.

[0014] Furthermore, the amount of the chain transfer agent is 0.1-1% of the total mass of the monomers.

[0015] The total mass of monomers in the present invention refers to the total mass of the polyether monomer, the carboxylic acid monomer and the organosilicon monomer.

[0016] A second object of the present invention is to provide a polycarboxylate water-reducing agent prepared by the aforementioned preparation method.

[0017] Furthermore, the weight average molecular weight of the polycarboxylate water reducer is 30,000-50,000.

[0018] A third object of the present invention is to provide the use of the polycarboxylate water-reducing agent as a cement dispersant.

[0019] Furthermore, the dosage of the polycarboxylate water-reducing agent is 0.25-1% of the mass of the cement, calculated as the solid dosage of the polycarboxylate water-reducing agent.

[0020] The beneficial effects of the present invention are as follows: the polycarboxylate water-reducing agent of the present invention has excellent water-reducing and slump-retaining properties under low dosage conditions, can not only reduce the amount of water used in concrete mixing, but also achieve uniform dispersion of cement particles in concrete, improve the fluidity and filling properties of concrete, make concrete easier to construct and form, but also improve the strength and durability of concrete, and is suitable for different types of cement. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific embodiments.

[0022] Ingredients Description:

[0023] Allyl alcohol polyoxyethylene ether was purchased from Hai'an Petrochemical Plant, Jiangsu Province, model APEG-700;

[0024] Isoprenol polyoxyethylene ether was purchased from Hubei Hengjingrui Chemical Co., Ltd., model TPEG2000;

[0025] Isobutenol polyoxyethylene ether was purchased from Zhejiang Kaide Chemical Co., Ltd., model TPEG 2400 S5.

[0026] Example 1

[0027] To 250 mL of N,N-dimethylformamide, add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine, and 0.11 mol of N,N-diisopropylethylamine. Heat to 40°C and allow to react for 5 h. After the reaction, add 300 mL of water to the reaction solution and stir. The precipitated solid was filtered, washed with water, and dried under vacuum to obtain the organosilicon monomer.

[0028] To 50 g of deionized water, 50 g of allyl alcohol polyoxyethylene ether, 10 g of the organosilicon monomer prepared in Example 1, and 1 g of potassium persulfate were added. The air in the reactor was replaced with nitrogen, the temperature was raised to 60° C., and a mixed solution consisting of 200 g of acrylic acid, 0.5 g of L-ascorbic acid, 1 g of thioglycolic acid, and 100 g of deionized water was added dropwise. After the addition was complete, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0029] Example 2

[0030] To 250 mL of N,N-dimethylformamide, add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.105 mol of 2-(methylsulfonyl)ethylamine, and 0.105 mol of triethylamine. Heat to 40°C and allow to react for 5 hours. After the reaction, add 300 mL of water to the reaction solution and stir. The precipitated solid was filtered, washed with water, and dried under vacuum to obtain the organosilicon monomer.

[0031] To 50 g of deionized water, 50 g of isopentanol polyoxyethylene ether, 15 g of the organosilicon monomer prepared in Example 2, and 1 g of potassium persulfate were added. The air in the reactor was replaced with nitrogen, the temperature was raised to 60° C., and a mixed solution consisting of 200 g of methacrylic acid, 0.8 g of sodium sulfite, 1.5 g of mercaptopropionic acid, and 100 g of deionized water was added dropwise. After the addition was complete, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0032] Example 3

[0033] To 250 mL of N,N-dimethylformamide, add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine, and 0.11 mol of pyridine. Heat to 40°C and allow to react for 5 h. After the reaction, add 300 mL of water to the reaction solution and stir. The precipitated solid was filtered, washed with water, and dried under vacuum to obtain the organosilicon monomer.

[0034] To 50 g of deionized water, 50 g of isobutylene alcohol polyoxyethylene ether, 15 g of the organosilicon monomer prepared in Example 3, and 1.5 g of ammonium persulfate were added. The air in the reactor was replaced with nitrogen, the temperature was raised to 60° C., and a mixed solution consisting of 180 g of itaconic acid, 1 g of ferrous sulfate, 1.5 g of mercaptopropanol, and 100 g of deionized water was added dropwise. After the addition was complete, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0035] Example 4

[0036] To 250 mL of N,N-dimethylformamide, add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine, and 0.11 mol of N,N-diisopropylethylamine. Heat to 50°C and allow to react for 4 h. After the reaction, add 300 mL of water to the reaction solution and stir. The precipitated solid was filtered, washed with water, and dried under vacuum to obtain the organosilicon monomer.

[0037] To 50 g of deionized water, 50 g of allyl alcohol polyoxyethylene ether, 20 g of the organosilicon monomer prepared in Example 4, and 1 g of ammonium persulfate were added. The air in the reactor was replaced with nitrogen, the temperature was raised to 60° C., and a mixed solution consisting of 150 g of maleic acid, 0.8 g of ferrous chloride, 1 g of mercaptoethanol, and 100 g of deionized water was added dropwise. After the addition was complete, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0038] Example 5

[0039] To 250 mL of N,N-dimethylformamide, add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine, and 0.11 mol of triethylamine. The mixture was reacted at 25°C for 8 h. After the reaction, 300 mL of water was added to the reaction solution and stirred. The precipitated solid was filtered, washed with water, and dried under vacuum to obtain the organosilicon monomer.

[0040] To 50 g of deionized water, 50 g of isopentanol polyoxyethylene ether, 25 g of the organosilicon monomer prepared in Example 5, and 1 g of potassium persulfate were added. The air in the reactor was replaced with nitrogen, the temperature was raised to 60° C., and a mixed solution consisting of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid, and 100 g of deionized water was added dropwise. After the addition was complete, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0041] Comparative Example 1

[0042] Comparative Example 1 was obtained by replacing the 2-(methylsulfonyl)ethylamine added during the preparation of the organosilicon monomer in Example 5 with n-propylamine.

[0043] To 250 mL of N,N-dimethylformamide, add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of n-propylamine, and 0.11 mol of triethylamine. The mixture was reacted at 25°C for 8 h. After the reaction, 300 mL of water was added to the reaction solution and stirred. The precipitated solid was filtered, washed with water, and dried under vacuum to obtain an organosilicon monomer.

[0044] To 50 g of deionized water, 50 g of isopentanol polyoxyethylene ether, 25 g of the organosilicon monomer prepared in Comparative Example 1, and 1 g of potassium persulfate were added. The air in the reactor was replaced with nitrogen, the temperature was raised to 60° C., and a mixed solution consisting of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid, and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0045] Comparative Example 2

[0046] The organic silicon monomer added during the preparation of the polycarboxylate water-reducing agent in Example 5 was deleted, that is, no organic silicon monomer was added, to obtain Comparative Example 2.

[0047] 50 g of isopentanol polyoxyethylene ether and 1 g of potassium persulfate were added to 50 g of deionized water, the air in the reactor was replaced with nitrogen, the temperature was raised to 60°C, and a mixed solution consisting of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0048] Comparative Example 3

[0049] The organosilicon monomer added when preparing the polycarboxylate water-reducing agent in Example 5 was replaced with allyldimethylsilane to obtain Comparative Example 3.

[0050] 50 g of isopentanol polyoxyethylene ether, 25 g of allyldimethylsilane and 1 g of potassium persulfate were added to 50 g of deionized water, the air in the reactor was replaced with nitrogen, the temperature was raised to 60°C, and a mixed solution consisting of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0051] Comparative Example 4

[0052] The organic silicon monomer added in the preparation of the polycarboxylate water-reducing agent in Example 5 was replaced with 3-(trimethoxysilyl)propyl methacrylate to obtain Comparative Example 4.

[0053] 50 g of isopentanol polyoxyethylene ether, 25 g of 3-(trimethoxysilyl)propyl methacrylate and 1 g of potassium persulfate were added to 50 g of deionized water. The air in the reactor was replaced with nitrogen. The temperature was raised to 60°C, and a mixed solution consisting of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0054] The polycarboxylate water-reducing agents prepared in the above examples and comparative examples were each incorporated into concrete at a solids content of 0.25% by weight of cement. The concrete composition consisted of PO42.5 cement, 0.35-0.5 mm sand, 5-15 mm crushed stone, and water in a mass ratio of 300:600:800:150. The water reduction rate, slump, and compressive strength of the concrete were tested according to GB 8076-2008, "Concrete Admixtures." Each sample was tested five times, and the average value was calculated. The test results are shown in Table 1.

[0055] Table 1 Performance test results of polycarboxylate water reducer

[0056]

[0057] As shown in Table 1, compared with Comparative Examples 1 to 3, Examples 1 to 5 can substantially improve the water-reducing and slump-retaining properties of concrete and significantly improve the strength of concrete by adding an organosilicon monomer synthesized from allyl (chloromethyl) dimethylsilane and 2-(methylsulfonyl) ethylamine as a comonomer during the preparation of the polycarboxylate water-reducing agent.

[0058] In order to further improve the performance of polycarboxylic acid water-reducing agent, the present invention also conducted in-depth research on carboxylic acid monomers, and found that an appropriate amount of 2-methacrylic acid zinc salt can be added to the above-mentioned carboxylic acid monomers (including but not limited to at least one of acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid).

[0059] A fourth object of the present invention is to provide a method for preparing a polycarboxylic acid water reducer, wherein a polyether monomer, a carboxylic acid monomer and 2-methacrylic acid zinc salt are subjected to a free radical copolymerization reaction under the action of an initiator and a chain transfer agent to obtain a polycarboxylic acid water reducer.

[0060] Furthermore, the mass ratio of the polyether monomer, carboxylic acid monomer, and 2-methacrylate zinc salt is 1:(3-4):(0.1-0.3). Compared with the synthesis of the above-mentioned organosilicon monomer, directly adding 2-methacrylate zinc salt as a comonomer has the advantage of simple operation.

[0061] Furthermore, the polyether monomer includes but is not limited to at least one of allyl alcohol polyoxyethylene ether, isopentenol polyoxyethylene ether, isobutylenol polyoxyethylene ether, and methylallyl alcohol polyoxyethylene ether.

[0062] Furthermore, the carboxylic acid monomer includes but is not limited to at least one of acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.

[0063] Furthermore, the initiator is a redox initiator, comprising an oxidizing agent and a reducing agent. The oxidizing agent includes, but is not limited to, at least one of hydrogen peroxide, potassium persulfate, ammonium persulfate, and sodium persulfate. The reducing agent includes, but is not limited to, at least one of L-ascorbic acid, sodium sulfite, sodium bisulfite, ferrous sulfate, and ferrous chloride. Redox initiators generate free radicals through redox reactions, thereby initiating polymerization reactions.

[0064] Furthermore, the chain transfer agent includes but is not limited to at least one of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol. The main function of the chain transfer agent is to regulate the activity and stability of free radicals, thereby controlling the molecular weight and molecular weight distribution of the polymer.

[0065] Furthermore, the amount of the initiator used is 0.1-1% of the total weight of the monomers. If the amount of initiator used is too little, the polymerization reaction will be slow or incomplete; if the amount of initiator used is too much, the polymerization reaction will be too fast, which may result in a lower molecular weight of the polymer and a wider molecular weight distribution.

[0066] Furthermore, the amount of the chain transfer agent is 0.1-1% of the total mass of the monomers.

[0067] The total mass of monomers in the present invention refers to the total mass of the polyether monomer, the carboxylic acid monomer and the 2-methacrylic acid zinc salt.

[0068] A fifth object of the present invention is to provide a polycarboxylate water-reducing agent prepared by the aforementioned preparation method.

[0069] Furthermore, the weight average molecular weight of the polycarboxylate water reducer is 30,000-50,000.

[0070] A sixth object of the present invention is to provide the use of the polycarboxylate water-reducing agent as a cement dispersant.

[0071] Furthermore, the dosage of the polycarboxylate water-reducing agent is 0.25-1% of the mass of the cement, calculated as the solid dosage of the polycarboxylate water-reducing agent.

[0072] Example 6

[0073] 50 g of isopentanol polyoxyethylene ether, 5 g of 2-methacrylic acid zinc salt and 1 g of potassium persulfate were added to 50 g of deionized water. The air in the reactor was replaced with nitrogen. The temperature was raised to 60°C, and a mixed solution consisting of 200 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0074] Example 7

[0075] 50 g of isopentanol polyoxyethylene ether, 10 g of 2-methacrylic acid zinc salt and 1 g of potassium persulfate were added to 50 g of deionized water. The air in the reactor was replaced with nitrogen. The temperature was raised to 60°C, and a mixed solution consisting of 180 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0076] Example 8

[0077] 50 g of isopentanol polyoxyethylene ether, 15 g of 2-methacrylate zinc salt and 1 g of potassium persulfate were added to 50 g of deionized water. The air in the reactor was replaced with nitrogen. The temperature was raised to 60°C, and a mixed solution consisting of 150 g of methacrylic acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0078] Comparative Example 5

[0079] The 2-methacrylic acid zinc salt in Example 6 was deleted, that is, no 2-methacrylic acid zinc salt was added, to obtain Comparative Example 5.

[0080] 50 g of isopentanol polyoxyethylene ether and 1 g of potassium persulfate were added to 50 g of deionized water, the air in the reactor was replaced with nitrogen, the temperature was raised to 60°C, and a mixed solution consisting of 200 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0081] Comparative Example 6

[0082] The 2-methacrylic acid zinc salt in Example 7 was deleted, that is, no 2-methacrylic acid zinc salt was added, to obtain Comparative Example 7.

[0083] 50 g of isopentanol polyoxyethylene ether and 1 g of potassium persulfate were added to 50 g of deionized water, the air in the reactor was replaced with nitrogen, the temperature was raised to 60°C, and a mixed solution consisting of 180 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0084] Comparative Example 7

[0085] The 2-methacrylic acid zinc salt in Example 8 was deleted, that is, no 2-methacrylic acid zinc salt was added, to obtain Comparative Example 7.

[0086] 50 g of isopentanol polyoxyethylene ether and 1 g of potassium persulfate were added to 50 g of deionized water, the air in the reactor was replaced with nitrogen, the temperature was raised to 60°C, and a mixed solution consisting of 150 g of methacrylic acid, 1 g of L-ascorbic acid, 1.5 g of thioglycolic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept warm for 2 h and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0087] The polycarboxylate water-reducing agents prepared in the above examples and comparative examples were each incorporated into concrete at a solids content of 0.25% by weight of cement. The concrete composition consisted of PI42.5 cement, 0.35-0.5 mm sand, 5-15 mm crushed stone, and water in a mass ratio of 300:700:850:150. The water reduction rate, slump, and compressive strength of the concrete were tested according to GB 8076-2008, "Concrete Admixtures." Each sample was tested five times, and the average value was calculated. The test results are shown in Table 2.

[0088] Table 2 Performance test results of polycarboxylate water reducer

[0089]

[0090] As shown in Table 2, compared with Comparative Examples 5 to 7, Examples 6 to 8 can substantially improve the water-reduction and slump-retention properties of concrete and significantly improve the strength of concrete by adding 2-methacrylate zinc salt as a comonomer during the preparation of the polycarboxylate water-reducing agent.

[0091] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a polycarboxylate water-reducing agent, characterized in that: The polyether monomer, the carboxylic acid monomer and the silicone monomer are subjected to a free radical copolymerization reaction under the action of an initiator and a chain transfer agent to obtain a polycarboxylic acid water reducer; The organosilicon monomer is obtained by a substitution reaction between allyl (chloromethyl) dimethylsilane and 2-(methylsulfonyl) ethylamine under the action of an acid binding agent; The mass ratio of the polyether monomer, the carboxylic acid monomer, and the silicone monomer is 1: (3-4): (0.2-0.5).

2. The preparation method according to claim 1, wherein: The acid binding agent is selected from at least one of potassium carbonate, sodium carbonate, sodium hydroxide, sodium acetate, triethylamine, pyridine, and N,N-diisopropylethylamine; The molar ratio of allyl (chloromethyl) dimethylsilane, 2-(methylsulfonyl) ethylamine, and acid binding agent is 1: (1-1.1): (1-1.1).

3. The preparation method according to claim 1, wherein: The polyether monomer is selected from at least one of allyl alcohol polyoxyethylene ether, isopentenol polyoxyethylene ether, isobutylenol polyoxyethylene ether, and methylallyl alcohol polyoxyethylene ether.

4. The preparation method according to claim 1, wherein: The carboxylic acid monomer is selected from at least one of acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.

5. The preparation method according to claim 1, wherein: The initiator is a redox initiator, comprising an oxidizing agent and a reducing agent; The oxidant is selected from at least one of hydrogen peroxide, potassium persulfate, ammonium persulfate, and sodium persulfate; The reducing agent is selected from at least one of L-ascorbic acid, sodium sulfite, sodium bisulfite, ferrous sulfate, and ferrous chloride.

6. The preparation method according to claim 1, wherein: The chain transfer agent is selected from at least one of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol.

7. The preparation method according to claim 1, wherein: The amount of the initiator is 0.1-1% of the total mass of the monomer; The amount of the chain transfer agent used is 0.1-1% of the total weight of the monomers.

8. A polycarboxylate water-reducing agent, prepared by the preparation method according to any one of claims 1 to 7.

9. The polycarboxylate water-reducing agent according to claim 8, characterized in that: The weight average molecular weight of the polycarboxylate water reducer is 30,000-50,000.

10. Use of the polycarboxylate water-reducing agent according to claim 8 or 9 as a cement dispersant.

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