High-slump-loss-resistant polycarboxylic acid water reducing agent and preparation method and application thereof

Abstract

The invention discloses a high slump loss resistant polycarboxylic acid water reducing agent and a preparation method and application thereof, and relates to the technical field of polycarboxylic acid water reducing agents. Polyether monomers, carboxylic acid monomers and organic silicon monomers are subjected to free radical copolymerization under the action of an initiator and a chain transfer agent, and the polycarboxylic acid water reducing agent is obtained; the polycarboxylate superplasticizer disclosed by the invention has excellent water reducing and slump retaining properties under the condition of low mixing amount, the water consumption for mixing concrete can be reduced, cement particles can be uniformly dispersed in the concrete, the flowability and the filling property of the concrete are improved, the concrete is easy to construct and form, and the strength and the durability of the concrete are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polycarboxylate superplasticizers, and particularly relates to a high slump retention polycarboxylate superplasticizer, a preparation method thereof and uses thereof. Background Art

[0002] As a high-performance superplasticizer, polycarboxylate superplasticizer plays a crucial role in cement concrete projects and is widely used in projects such as highways, bridges, dams, tunnels and high-rise buildings. Since polycarboxylate superplasticizer has the characteristics of being non-flammable and non-explosive, it can be safely transported. According to the different main chain structures, polycarboxylate superplasticizers can be divided into two categories. One category is based on acrylic acid or methacrylic acid as the main chain and grafted with polyethers of different side chain lengths; the other category is based on maleic anhydride as the main chain and grafted with polyethers of different side chain lengths.

[0003] The transportation process of concrete from the mixing plant to the construction site will inevitably lead to a decrease in the fluidity of concrete, thus accelerating the slump loss. Moreover, the concrete mixed with polycarboxylate superplasticizer has less mixing water consumption, which will also lead to an accelerated slump loss of the concrete and an increase in viscosity, affecting the normal construction of the concrete and making it difficult to ensure the quality of the concrete. Although the method of adding retarders can improve the slump retention ability of concrete, it cannot fundamentally solve the problem of slump loss; at the same time, there may be compatibility problems between the retarder and the superplasticizer and between the retarder and the cement, thus affecting the performance of the concrete. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method of a high slump retention polycarboxylate superplasticizer. The obtained polycarboxylate superplasticizer can be used as a cement dispersant, showing excellent water reducing and slump retention properties, and improving the construction effect and quality of concrete.

[0005] The technical problem to be solved by the present invention is achieved by the following technical solutions: One object of the present invention is to provide a preparation method of a polycarboxylate superplasticizer, in which 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 a polycarboxylate superplasticizer.

[0006] Further, the organosilicon monomer is obtained by a substitution reaction of allyl(chloromethyl)dimethylsilane and 2-(methylsulfonyl)ethylamine under the action of an acid-binding agent. Among them, 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)dimethylsilane, 2-(methylsulfonyl)ethylamine, and the acid-binding agent is 1 : (1~1.1) : (1~1.1). The acid-binding agent accelerates the reaction rate by neutralizing hydrogen chloride generated in the substitution reaction. Appropriate excess of 2-(methylsulfonyl)ethylamine and the acid-binding agent can increase the conversion rate of allyl(chloromethyl)dimethylsilane and the yield of the organosilicon monomer.

[0007] Further, the polyether monomer includes but is not limited to at least one of allyl alcohol polyoxyethylene ether, isopentenol polyoxyethylene ether, isobutenol polyoxyethylene ether, and methallyl alcohol polyoxyethylene ether.

[0008] Further, 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.

[0009] Further, the initiator is a redox initiator, including an oxidizing agent and a reducing agent. Among them, 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. The redox initiator generates free radicals through a redox reaction, thereby initiating the polymerization reaction.

[0010] Further, 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.

[0011] Further, the mass ratio of the polyether monomer, carboxylic acid monomer, and organosilicon monomer is 1 : (3~4) : (0.2~0.5). With the carboxylic acid monomer as the main component and adding appropriate amounts of the polyether monomer and organosilicon monomer, a polycarboxylate water reducer with a specific structure is synthesized.

[0012] Further, the dosage of the initiator is 0.1~1% of the total mass of the monomers. When the dosage of the initiator is too small, the polymerization reaction is slow or incomplete; when the dosage of the initiator is too large, the polymerization reaction is too fast, which may cause a decrease in the molecular weight of the polymer and a wider molecular weight distribution.

[0013] Further, the dosage of the chain transfer agent is 0.1~1% of the total mass of the monomers.

[0014] The total mass of monomers in the present invention refers to the total mass of polyether monomers, carboxylic acid monomers and organosilicon monomers.

[0015] The second object of the present invention is to provide a polycarboxylate water reducer prepared by the aforementioned preparation method.

[0016] Furthermore, the weight-average molecular weight of the polycarboxylate water reducer is 30,000 - 50,000.

[0017] The third object of the present invention is to provide the use of the polycarboxylate water reducer as a cement dispersant.

[0018] Furthermore, the dosage of the polycarboxylate water reducer is 0.25 - 1% of the mass of cement, calculated based on the solid content of the polycarboxylate water reducer.

[0019] The beneficial effects of the present invention are as follows: The polycarboxylate water reducer of the present invention has excellent water-reducing and slump-retention properties under low dosage conditions. It can not only reduce the water consumption in concrete mixing, achieve uniform dispersion of cement particles in concrete, improve the fluidity and filling property of concrete, making the concrete easy to construct and form, but also improve the strength and durability of concrete, and is applicable to different types of cement. Detailed Embodiments

[0020] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0021] Raw Material Description: Allyl alcohol polyoxyethylene ether was purchased from Hai'an Petrochemical Factory, Jiangsu Province, with the model APEG-700; Isopentenol polyoxyethylene ether was purchased from Hubei Hengjingrui Chemical Co., Ltd., with the model TPEG2000; Isobutenol polyoxyethylene ether was purchased from Zhejiang Kaide Chemical Co., Ltd., with the model TPEG 2400 S5.

[0022] Example 1 Add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine and 0.11 mol of N,N-diisopropylethylamine to 250 mL of N,N-dimethylformamide, and heat to 40 °C for reaction for 5 h. After the reaction is completed, add 300 mL of water to the reaction solution, stir, precipitate solids, filter, wash with water, and dry under vacuum to obtain the organosilicon monomer.

[0023] Add 50 g of allyl alcohol polyoxyethylene ether, 10 g of the organosilicon monomer prepared in Example 1, and 1 g of potassium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 200 g of acrylic acid, 0.5 g of L-ascorbic acid, 1 g of mercaptoacetic acid, and 100 g of deionized water. After the dropwise addition is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0024] Example 2 Add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.105 mol of 2-(methylsulfonyl)ethylamine, and 0.105 mol of triethylamine to 250 mL of N,N-dimethylformamide, and heat up to 40 °C for reaction for 5 h. After the reaction is completed, add 300 mL of water to the reaction solution, stir, precipitate solids, filter, wash with water, and dry in vacuum to obtain an organosilicon monomer.

[0025] Add 50 g of isopentenol polyoxyethylene ether, 15 g of the organosilicon monomer prepared in Example 2, and 1 g of potassium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 200 g of methacrylic acid, 0.8 g of sodium sulfite, 1.5 g of mercaptopropionic acid, and 100 g of deionized water. After the dropwise addition is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0026] Example 3 Add 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine, and 0.11 mol of pyridine to 250 mL of N,N-dimethylformamide, and heat up to 40 °C for reaction for 5 h. After the reaction is completed, add 300 mL of water to the reaction solution, stir, precipitate solids, filter, wash with water, and dry in vacuum to obtain an organosilicon monomer.

[0027] Add 50 g of isobutenol polyoxyethylene ether, 15 g of the organosilicon monomer prepared in Example 3, and 1.5 g of ammonium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 180 g of itaconic acid, 1 g of ferrous sulfate, 1.5 g of mercaptopropanol, and 100 g of deionized water. After the dropwise addition is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0028] Example 4 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine and 0.11 mol of N,N-diisopropylethylamine were added to 250 mL of N,N-dimethylformamide, and the temperature was raised to 50 °C and reacted for 4 h. After the reaction was completed, 300 mL of water was added to the reaction solution, stirred, and a solid was precipitated, filtered, washed with water, and dried in vacuo to obtain an organosilicon monomer.

[0029] 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 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 composed 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 completed, the reaction was kept warm for 2 h, and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0030] Example 5 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of 2-(methylsulfonyl)ethylamine and 0.11 mol of triethylamine were added to 250 mL of N,N-dimethylformamide, and the reaction was carried out at 25 °C for 8 h. After the reaction was completed, 300 mL of water was added to the reaction solution, stirred, and a solid was precipitated, filtered, washed with water, and dried in vacuo to obtain an organosilicon monomer.

[0031] 50 g of isopentenol polyoxyethylene ether, 25 g of the organosilicon monomer prepared in Example 5 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 composed of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid and 100 g of deionized water was added dropwise. After the addition was completed, the reaction was kept warm for 2 h, and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0032] Comparative Example 1 In Comparative Example 1, 2-(methylsulfonyl)ethylamine added when preparing the organosilicon monomer in Example 5 was replaced with n-propylamine.

[0033] 0.1 mol of allyl(chloromethyl)dimethylsilane, 0.11 mol of n-propylamine and 0.11 mol of triethylamine were added to 250 mL of N,N-dimethylformamide, and the reaction was carried out at 25 °C for 8 h. After the reaction was completed, 300 mL of water was added to the reaction solution, stirred, and a solid was precipitated, filtered, washed with water, and dried in vacuo to obtain an organosilicon monomer.

[0034] Add 50 g of isopentenyl polyoxyethylene ether, 25 g of the organosilicon monomer prepared in Comparative Example 1, and 1 g of potassium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropwise addition is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0035] Comparative Example 2 Delete the organosilicon monomer added when preparing the polycarboxylate water reducer in Example 5, that is, do not add the organosilicon monomer, to obtain Comparative Example 2.

[0036] Add 50 g of isopentenyl polyoxyethylene ether and 1 g of potassium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropwise addition is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0037] Comparative Example 3 Replace the organosilicon monomer added when preparing the polycarboxylate water reducer in Example 5 with allyldimethylsilane to obtain Comparative Example 3.

[0038] Add 50 g of isopentenyl polyoxyethylene ether, 25 g of allyldimethylsilane, and 1 g of potassium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropwise addition is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0039] Comparative Example 4 Replace the organosilicon monomer added when preparing the polycarboxylate water reducer in Example 5 with 3-(trimethoxysilyl)propyl methacrylate to obtain Comparative Example 4.

[0040] Add 50 g of isopentenyl polyoxyethylene ether, 25 g of 3-(trimethoxysilyl)propyl methacrylate, and 1 g of potassium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 100 g of acrylic acid, 50 g of fumaric acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropwise addition is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0041] The polycarboxylate water reducer prepared in the above-mentioned examples and comparative examples was incorporated into concrete respectively. The solid content of the water reducer was 0.25% of the mass of cement. The composition of the concrete was as follows: the mass ratio of PO42.5 cement, sand with a size of 0.35 - 0.5 mm, gravel with a size of 5 - 15 mm, and water was 300 : 600 : 800 : 150. The water reduction rate, slump, and compressive strength of the concrete were tested in accordance with the standard GB 8076 - 2008 "Concrete Admixtures". Each group of samples was tested 5 times, and the average value was taken. The test results are shown in Table 1.

[0042] Table 1 Performance test results of polycarboxylate water reducer

[0043] As can be seen from Table 1, compared with Comparative Examples 1 - 3, in Examples 1 - 5, by adding an organosilicon monomer synthesized from allyl(chloromethyl)dimethylsilane and 2-(methylsulfonyl)ethylamine as a comonomer during the preparation of the polycarboxylate water reducer, not only can the water reduction and slump retention performance of the concrete be substantially improved, but also the strength of the concrete can be significantly increased.

[0044] In order to further improve the performance of the polycarboxylate water reducer, the present invention also conducted in - depth research on the carboxylic acid monomer, and it was found that an appropriate amount of zinc 2 - methylacrylate can be added based on the above - mentioned carboxylic acid monomers (including but not limited to at least one of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid).

[0045] The fourth object of the present invention is to provide a preparation method of a polycarboxylate water reducer. The polyether monomer, carboxylic acid monomer, and zinc 2 - methylacrylate are subjected to free - radical copolymerization under the action of an initiator and a chain transfer agent to obtain the polycarboxylate water reducer.

[0046] Furthermore, the mass ratio of the polyether monomer, carboxylic acid monomer, and zinc 2 - methylacrylate is 1 : (3 - 4) : (0.1 - 0.3). Compared with the synthesis of the above - mentioned organosilicon monomer, directly adding zinc 2 - methylacrylate as a comonomer has the advantage of simple operation.

[0047] Furthermore, the polyether monomer includes but is not limited to at least one of allyl alcohol polyoxyethylene ether, isopentenol polyoxyethylene ether, isobutenol polyoxyethylene ether, and methallyl alcohol polyoxyethylene ether.

[0048] 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.

[0049] Further, the initiator is a redox initiator, including an oxidant and a reductant. Among them, the oxidant includes but is not limited to at least one of hydrogen peroxide, potassium persulfate, ammonium persulfate, and sodium persulfate. The reductant includes but is not limited to at least one of L-ascorbic acid, sodium sulfite, sodium bisulfite, ferrous sulfate, and ferrous chloride. The redox initiator generates free radicals through a redox reaction, thereby initiating the polymerization reaction.

[0050] Further, 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.

[0051] Further, the dosage of the initiator is 0.1-1% of the total mass of the monomers. When the dosage of the initiator is too small, the polymerization reaction is slow or incomplete; when the dosage of the initiator is too large, the polymerization reaction is too fast, which may cause a decrease in the molecular weight of the polymer and a wide molecular weight distribution.

[0052] Further, the dosage of the chain transfer agent is 0.1-1% of the total mass of the monomers.

[0053] The total mass of the monomers in the present invention refers to the total mass of the polyether monomer, the carboxylic acid monomer, and the zinc 2-methylacrylate salt.

[0054] The fifth object of the present invention is to provide a polycarboxylate water reducer prepared by the foregoing preparation method.

[0055] Further, the weight-average molecular weight of the polycarboxylate water reducer is 30,000-50,000.

[0056] The sixth object of the present invention is to provide the use of the polycarboxylate water reducer as a cement dispersant.

[0057] Further, the dosage of the polycarboxylate water reducer is 0.25-1% of the mass of the cement, based on the solid content of the polycarboxylate water reducer.

[0058] Example 6

[0059] Add 50 g of isopentenyl polyoxyethylene ether, 5 g of zinc 2-methylacrylate salt, and 1 g of potassium persulfate to 50 g of deionized water. Replace the air in the reactor with nitrogen, heat up to 60°C, and dropwise add a mixed solution composed of 200 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropping is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0060] Example 7

[0061] To 50 g of deionized water, add 50 g of isopentenyl alcohol polyoxyethylene ether, 10 g of zinc 2-methylacrylate, and 1 g of potassium persulfate. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 180 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropping is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0062] Example 8

[0063] To 50 g of deionized water, add 50 g of isopentenyl alcohol polyoxyethylene ether, 15 g of zinc 2-methylacrylate, and 1 g of potassium persulfate. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 150 g of methacrylic acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropping is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0064] Comparative Example 5 Delete the zinc 2-methylacrylate in Example 6, that is, do not add zinc 2-methylacrylate, to obtain Comparative Example 5.

[0065] To 50 g of deionized water, add 50 g of isopentenyl alcohol polyoxyethylene ether and 1 g of potassium persulfate. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 200 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropping is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0066] Comparative Example 6 Delete the zinc 2-methylacrylate in Example 7, that is, do not add zinc 2-methylacrylate, to obtain Comparative Example 7.

[0067] To 50 g of deionized water, add 50 g of isopentenyl alcohol polyoxyethylene ether and 1 g of potassium persulfate. Replace the air in the reactor with nitrogen, heat up to 60 °C, and dropwise add a mixed solution composed of 180 g of acrylic acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid, and 100 g of deionized water. After the dropping is completed, keep the reaction at a constant temperature for 2 h, and adjust the pH to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0068] Comparative Example 7 Delete the zinc 2-methylacrylate in Example 8, that is, do not add zinc 2-methylacrylate, to obtain Comparative Example 7.

[0069] 50 g of isopentenyl alcohol 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, and the temperature was raised to 60 °C. A mixed solution composed of 150 g of methacrylic acid, 1 g of L-ascorbic acid, 1.5 g of mercaptoacetic acid and 100 g of deionized water was added dropwise. After the addition was completed, the mixture was kept reacting for 2 h, and the pH was adjusted to neutral with sodium hydroxide solution to obtain a polycarboxylate water reducer.

[0070] The polycarboxylate water reducers prepared in the above examples and comparative examples were respectively incorporated into concrete. The solid dosage of the water reducer was 0.25% of the mass of cement. The composition of the concrete: the mass ratio of PI42.5 cement, 0.35 - 0.5 mm sand, 5 - 15 mm gravel and water was 300 : 700 : 850 : 150. According to the standard GB 8076 - 2008 "Concrete Admixtures", the water reduction rate, slump and compressive strength of the concrete were tested. Each group of samples was tested 5 times, and the average value was taken. The test results are shown in Table 2.

[0071] Table 2 Performance test results of polycarboxylate water reducers

[0072] As can be seen from Table 2, compared with Comparative Examples 5 - 7, in Examples 5 - 7, by adding zinc 2-methylacrylate as a comonomer during the preparation of the polycarboxylate water reducer, not only can the water reduction and slump retention performance of the concrete be substantially improved, but also the strength of the concrete can be significantly increased.

[0073] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a polycarboxylate water reducer, characterized in that: A polycarboxylate water reducer is obtained by carrying out free radical copolymerization of a polyether monomer, a carboxylic acid monomer and a silicone monomer under the action of an initiator and a chain transfer agent.

2. The preparation method according to claim 1, characterized in that: The silicone monomer is obtained by a substitution reaction of allyl(chloromethyl)dimethylsilane and 2-(methylsulfonyl)ethylamine under the action of an acid-binding agent; The acid-binding agent is selected from at least one of potassium carbonate, sodium carbonate, sodium hydroxide, sodium acetate, triethylamine, pyridine, N,N-diisopropylethylamine; The molar ratio of allyl(chloromethyl)dimethylsilane, 2-(methylsulfonyl)ethylamine, and the 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, isobutenol polyoxyethylene ether, and methallyl alcohol polyoxyethylene ether.

4. The preparation method according to claim 1, characterized in that: 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, characterized in that: The initiator is a redox initiator, including an oxidant and a reductant; The oxidant is selected from at least one of hydrogen peroxide, potassium persulfate, ammonium persulfate, and sodium persulfate; The reductant 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, characterized in that: The chain transfer agent is selected from at least one of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and mercaptopropanol.

7. The preparation method according to claim 1, characterized in that: The mass ratio of the polyether monomer, the carboxylic acid monomer, and the silicone monomer is 1 : (3~4) : (0.2~0.5); The dosage of the initiator is 0.1~1% of the total mass of the monomers; The dosage of the chain transfer agent is 0.1~1% of the total mass of the monomers.

8. A polycarboxylate water reducer is prepared by the preparation method according to any one of claims 1~7.

9. The polycarboxylate water reducer according to claim 8, characterized in that: The weight average molecular weight of the polycarboxylate water reducer is 30000~50000.

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

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