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

Abstract

The present invention discloses a high water-reducing and high slump-retention polycarboxylate water reducer, which comprises an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer, an alkyne ester monomer, an oxidizing agent, a reducing agent and a chain transfer agent; the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer and the alkyne ester monomer is 1:0.5-3.5:0.1-2.5, the dosage of the oxidizing agent is 0.1%-1.5% of the total mass of the unsaturated polyether macromonomer, the dosage of the reducing agent is 0.1%-2.0% of the total mass of the unsaturated polyether macromonomer, and the dosage of the chain transfer agent is 0.1%-1.2% of the total mass of the unsaturated polyether macromonomer. The present invention also discloses a preparation method of the high water-reducing and high slump-retention polycarboxylate water reducer. The polycarboxylate water reducer of the present invention has both a rigid structure and a hydrolyzable group, which can greatly improve the slump-retention effect of concrete, and at the same time can also improve the strength of concrete and reduce the sensitivity of the polycarboxylate water reducer, weakening the negative effects of different concrete materials on the polycarboxylate water reducer and concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of water-reducing agents, and particularly relates to a high water-reducing and high slump-retention polycarboxylate water-reducing agent and a preparation method thereof. Background Art

[0002] With the strengthening of current environmental protection efforts, "restricted mining orders" have been implemented for natural sand and gravel, and a large amount of artificial manufactured sand has flowed into the market and is widely used in concrete. Due to the different production processes of current artificial manufactured sand, there are problems such as the deterioration of the stone gradation and the ineffective control of the sand gradation and mud content. Many factors have greatly reduced the slump-retention effect of concrete, causing serious problems for the long-distance transportation of concrete. Coupled with the current problem of hot weather, it has further caused losses to the concrete. Mixing plants hope to minimize the sensitivity of the admixture and improve the slump-retention effect of the admixture under the existing materials, while having little impact on the dosage of the admixture.

[0003] Currently, most polycarboxylate water-reducing agents pay more attention to the water reduction rate. For the slump-retention performance, a large amount of slump-retention agent is often added during the compounding process to achieve the slump-retention effect, which is extremely likely to bring drawbacks such as delayed concrete reaction. Relatively speaking, polycarboxylate water-reducing agents with slump-retention performance can achieve good slump-retention effects and greatly reduce the negative impact on concrete. However, some existing slump-retention polycarboxylate water-reducing agents have problems such as high sensitivity and slump-retention effects not meeting requirements, thus having a certain impact on the production of commercial concrete enterprises and on-site construction.

[0004] Through the synthetic technical means of admixtures, utilizing the low sensitivity and high adaptability of high water-reducing and high slump-retention water-reducing agents to continuously maintain the stability and time-dependent state of the concrete is one of the core technologies of admixtures that urgently need to be tackled and solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a high water-reducing and high slump-retention polycarboxylate water-reducing agent and a preparation method thereof, which are used to solve the technical problems that existing slump-retention polycarboxylate water-reducing agents have high sensitivity and slump-retention effects not meeting requirements.

[0006] To achieve the above purpose, in an embodiment of the present invention, a high water-reducing and high slump-retention polycarboxylate water-reducing agent is provided, which includes an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer, an alkyne ester monomer, an oxidizing agent, a reducing agent, and a chain transfer agent;

[0007] The molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer, and the alkyne ester monomer is 1:0.5 - 3.5:0.1 - 2.5. The dosage of the oxidizing agent is 0.1% - 1.5% of the total mass of the unsaturated polyether macromonomer, the dosage of the reducing agent is 0.1% - 2.0% of the total mass of the unsaturated polyether macromonomer, and the dosage of the chain transfer agent is 0.1% - 1.2% of the total mass of the unsaturated polyether macromonomer.

[0008] One of the preferred embodiments of the present invention is that the high water-reducing and high slump-retention polycarboxylate water reducer further includes a catalyst, and the catalyst is rhodium dichloride.

[0009] One of the preferred embodiments of the present invention is that part of the alkyne ester monomer is used as an anchor point for alkyne polymerization in olefin polymerization, and the other part is used for olefin polymerization, and the proportion of the alkyne ester monomer used for olefin polymerization is 70%-90%;

[0010] The dosage of the catalyst is 0.1%-5% of the weight of the alkyne ester monomer used for alkyne polymerization.

[0011] One of the preferred embodiments of the present invention is that the alkyne ester monomer is propargyl acrylate.

[0012] One of the preferred embodiments of the present invention is that the unsaturated polyether macromonomer is at least one of isopentenol polyoxyethylene ether, isobutenol polyoxyethylene ether, and methallyl alcohol polyoxyethylene ether.

[0013] One of the preferred embodiments of the present invention is that the unsaturated carboxylic acid monomer is at least one of acrylic acid, methacrylic acid, and maleic anhydride.

[0014] One of the preferred embodiments of the present invention is that the oxidant is at least one of ammonium persulfate, sodium persulfate, potassium persulfate, and hydrogen peroxide; the reducing agent is at least one of vitamin C, ferrous sulfate, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium hypophosphite, sodium formaldehyde sulfoxylate, and sodium dithionite; the chain transfer agent is at least one of mercaptoacetic acid, mercaptoethanol, mercaptopropionic acid, aliphatic mercaptan, dodecyl mercaptan, and sodium hydrogen phosphite.

[0015] Based on a high water-reducing and high slump-retention polycarboxylate water reducer disclosed in the present invention, the present invention also discloses a preparation method of a high water-reducing and high slump-retention polycarboxylate water reducer, including the following steps:

[0016] Step (1): Dissolve the unsaturated polyether macromonomer in water, and then add an oxidant to obtain a reactant solution;

[0017] Step (2): Dropwise add a mixed solution of an unsaturated carboxylic acid monomer and an alkyne ester monomer and a mixed solution of a reducing agent and a chain transfer agent to the obtained reactant solution respectively. After the dropping is completed, keep the temperature for reaction to obtain a high water-reducing and high slump-retention polycarboxylate water reducer.

[0018] One of the preferred embodiments of the present invention is that in step (2), the dropping time of the mixed solution of the unsaturated carboxylic acid monomer and the alkyne ester monomer is 30 min - 180 min, the dropping time of the mixed solution of the reducing agent and the chain transfer agent is 30 min - 180 min, the temperature for the heat preservation reaction is 20°C - 40°C, and the reaction time is 0.5 h - 2 h.

[0019] One of the preferred embodiments of the present invention is that in step (2), the conditions for dropping the mixed solution of the unsaturated carboxylic acid monomer and the alkynyl ester monomer and the mixed solution of the reducing agent and the chain transfer agent are: under stirring at 10°C - 60°C.

[0020] In summary, the beneficial effects of the present invention are as follows:

[0021] 1. In the present invention, a hydrophobic long side chain is introduced through an unsaturated polyether macromonomer to provide steric hindrance and other repulsive forces, which determine the dispersion and dispersion retention performance of the water reducer; a strongly polar anionic group is introduced into the main chain through an unsaturated carboxylic acid monomer, which mainly plays roles such as anchoring, solubilization, and providing electrostatic repulsion; through the introduction of the alkynyl ester monomer, on the one hand, an ester group containing a hydrolyzed carboxyl group undergoes hydrolysis in the alkaline environment of the cement paste through these groups, so as to continuously hydrolyze carboxyl groups for a long time, thereby improving the adsorption and dispersion ability in the later stage; on the other hand, the introduction of the alkynyl ester monomer introduces a triple bond on the side chain of the molecular chain, and the polymerization of the alkynyl group can be carried out to introduce a hydrophobic side chain again, which can effectively improve the molecular structure of the polycarboxylic acid water reducer (increase the rigidity of the molecular chain), and at the same time can also increase the dispersion and dispersion retention performance of the water reducer, showing characteristics such as low sensitivity, increased strength, reduced dosage, and improved slump retention effect in concrete, and having good adaptability to various materials; moreover, a double bond is introduced into the alkynyl ester monomer, which can participate in the free radical polymerization of olefins, and the unsaturated carboxylic acid is continuously generated after the hydrolysis of the ester group, playing roles of dispersion and slump retention. Utilizing the strongly polar anionic group of the carboxyl group, the hydrolysis of the ester group, and the rigidity of the polyalkyne molecular chain, the high slump retention type polycarboxylic acid water reducer shows characteristics of high water reduction, high slump retention performance, and low sensitivity, and can also improve the strength of concrete.

[0022] 2. The high water reduction and high slump retention type polycarboxylic acid water reducer of the present invention can effectively improve the disadvantages such as high dosage of the additive in concrete, great influence of materials on the additive, and serious loss of concrete by utilizing its characteristics of low sensitivity, reduced dosage, and increased strength. At the same time, by utilizing its improvement of the concrete performance, it can reduce the cost of the mixing plant, increase the material selection range of the mixing plant, and solve the problem of long-distance transportation under the existing materials.

[0023] 3. The ratios among the unsaturated polyether macromonomer, unsaturated carboxylic acid monomer, and alkyne ester monomer of the present invention have a great influence on the performance of the water reducer. If the molar ratio of the unsaturated carboxylic acid monomer to the polyether macromonomer (hereinafter referred to as the acid-ether ratio) is too low, the water reduction rate is low; if the acid-ether ratio is too high, the water reduction rate may be relatively large, and bleeding problems may occur in actual applications. If the molar ratio of the unsaturated carboxylic acid monomer to the alkyne ester monomer (hereinafter referred to as the acid-ester ratio) is too high, on the one hand, the number of carboxyl groups generated by the hydrolysis of the ester group is small, and the slump retention performance is poor; on the other hand, the reduction of the polyacetylene chain leads to a smaller molecular chain rigidity and a decrease in hydrophobic interaction, resulting in a reduced promotion effect on strength and being unfavorable for the dispersion of the water reducer, thereby reducing the water reduction rate of the water reducer; if the acid-ester ratio is too low, the number of carboxyl groups in the system is small, and the water reduction rate may decrease. Therefore, the acid-ether ratio, acid-ester ratio, dosage of the initiation system, and dosage of the chain transfer agent, etc. will all affect the water reduction rate and slump retention performance of the water reducer, and also affect the characteristics of the water reducer in improving the mechanical properties and workability of concrete.

[0024] 4. Under the specific molar ratio conditions of the unsaturated polyether macromonomer, unsaturated carboxylic acid monomer, and alkyne ester monomer of the present invention, high water reduction and high slump retention performance characteristics can be achieved, weakening the negative impacts of existing concrete materials on the additives and concrete performance, and at the same time improving the mechanical properties and workability of concrete. Specifically, by fixing the proportion of the unsaturated polyether macromonomer and adjusting the dosage of the unsaturated carboxylic acid monomer, the initial adsorption capacity of the polycarboxylate water reducer can be adjusted, thereby changing the water reduction rate of the polycarboxylate water reducer; by adjusting the dosage of the polyalkyne ester monomer, the later adsorption capacity of the polycarboxylate water reducer can be adjusted, thereby changing the slump retention performance of the polycarboxylate water reducer.

[0025] 5. The present invention introduces carbon-carbon triple bonds into the molecular structure through free radical polymerization and introduces polyacetylene chains through coordination polymerization. By adjusting the proportion of the unsaturated carboxylic acid monomer, a high water reduction and high slump retention type polycarboxylate water reducer with a rigid structure is synthesized. The specific reaction process is as follows:

[0026]

[0027] 6. The polycarboxylate water reducer of the present invention has both a rigid structure and a hydrolysis group, which can greatly improve the slump retention effect of concrete, and at the same time can also improve the strength of concrete and reduce the sensitivity of the polycarboxylate water reducer, weakening the negative impacts of different concrete materials on the polycarboxylate water reducer and concrete. Detailed Embodiments

[0028] The present invention discloses a high water reduction and high slump retention type polycarboxylate water reducer, which includes an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer, an alkyne ester monomer, an oxidant, a reductant, a chain transfer agent, and a catalyst;

[0029] Among them, the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer and the alkynyl ester monomer is 1:0.5 - 3.5:0.1 - 2.5. The dosage of the oxidant is 0.1% - 1.5% of the total mass of the unsaturated polyether macromonomer, the dosage of the reducing agent is 0.1% - 2.0% of the total mass of the unsaturated polyether macromonomer, and the dosage of the chain transfer agent is 0.1% - 1.2% of the total mass of the unsaturated polyether macromonomer; the alkynyl ester monomer is propynyl acrylate; part of the alkynyl ester monomer is used for olefin polymerization as an anchor for alkynyl polymerization, and the other part is used for alkyne polymerization, and the proportion of the alkynyl ester monomer used for olefin polymerization is 70% - 90%. The dosage of the catalyst is 0.1% - 5% of the weight of the alkynyl ester monomer used for alkyne polymerization;

[0030] The unsaturated polyether macromonomer is at least one of isopentenol polyoxyethylene ether, isobutenol polyoxyethylene ether and methallyl alcohol polyoxyethylene ether; the unsaturated carboxylic acid monomer is at least one of acrylic acid, methacrylic acid and maleic anhydride; the alkynyl ester monomer is propynyl acrylate; the oxidant is at least one of ammonium persulfate, sodium persulfate, potassium persulfate and hydrogen peroxide; the reducing agent is at least one of vitamin C, ferrous sulfate, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium hypophosphite, sodium formaldehyde sulfoxylate and sodium dithionite; the chain transfer agent is at least one of mercaptoacetic acid, mercaptoethanol, mercaptopropionic acid, aliphatic mercaptan, dodecyl mercaptan and sodium hydrogen phosphite; the catalyst is dichlororhodium (II) chloride.

[0031] A preparation method of a high water-reducing and high slump-retention polycarboxylate water reducer includes the following steps:

[0032] Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, sequentially add the unsaturated polyether macromonomer and water, stir at a low speed, and then add the oxidant to obtain a reactant solution;

[0033] Step (2): Dissolve the unsaturated carboxylic acid monomer and part of the alkynyl ester monomer used for olefin polymerization as an anchor for alkynyl polymerization in water, and stir and disperse evenly to obtain solution A; dissolve the reducing agent and the chain transfer agent in water, and stir and dissolve to obtain solution B;

[0034] Step (3): Under a stirring state at 10°C - 60°C, respectively dropwise add solution A and solution B to the reactant solution in step (1). Solution A is added dropwise for 30 min - 180 min, and solution B is added dropwise for 30 min - 180 min. After the dropping is completed, keep the temperature at 20°C - 40°C and carry out a heat preservation reaction for 0.5 h - 2.5 h to obtain solution C;

[0035] Step (4): Under a stirring state at 10°C - 60°C, add the other part of the alkynyl ester monomer used for alkyne polymerization and the catalyst to solution C, and keep the temperature for 3 h to obtain a high water-reducing and high slump-retention polycarboxylate water reducer.

[0036] Example 1

[0037] A high water-reducing and high slump-retention polycarboxylate superplasticizer, comprising 190 g of unsaturated polyether macromonomer isopentenol polyoxyethylene ether, 17.1 g of unsaturated carboxylic acid monomer acrylic acid, 6.97 g of alkyne ester monomer propynyl acrylate, 0.90 g of oxidant hydrogen peroxide, 0.30 g of reducing agent vitamin C, 0.50 g of chain transfer agent mercaptoethanol, and 7 mg of catalyst dichlororhodium (II) dimer;

[0038] Among them, the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer and the alkyne ester monomer is 1:3:0.8;

[0039] A preparation method of a high water-reducing and high slump-retention polycarboxylate superplasticizer, comprising the following steps:

[0040] Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, 190 g of isopentenol polyoxyethylene ether and 190 g of deionized water are added in sequence, stirred and dissolved at a low speed for 20 min, and then 0.90 g of hydrogen peroxide is added to obtain a reactant solution;

[0041] Step (2): 30.6 g of deionized water, 17.1 g of acrylic acid and 6.27 g of propynyl acrylate are stirred and dispersed evenly to obtain solution A, wherein 6.27 g of propynyl acrylate is dissolved in 3 ml of N,N-dimethylformamide; 42 g of water, 0.50 g of mercaptoethanol and 0.30 g of vitamin C are stirred and dissolved to obtain solution B;

[0042] Step (3): Under the condition of stirring at 30 °C, solution A and solution B are respectively added dropwise to the reactant solution in step (1). Solution A is added dropwise for 90 min, and solution B is added dropwise for 120 min. After the addition is completed, the mixture is kept warm and reacted at 40 °C for 1 h to obtain solution C;

[0043] Step (4): Under the condition of stirring at 30 °C, 0.7 g of propynyl acrylate and 7 mg of rhodium catalyst are added to solution C in sequence, and the mixture is kept warm for 3 h to obtain a high water-reducing and high slump-retention polycarboxylate superplasticizer, wherein 0.7 g of propynyl acrylate is dissolved in 0.5 ml of N,N-dimethylformamide.

[0044] Example 2

[0045] A high water-reducing and high slump-retention polycarboxylate superplasticizer, comprising 190 g of unsaturated polyether macromonomer methallyl alcohol polyoxyethylene ether, 12.53 g of unsaturated carboxylic acid monomer methacrylic acid, 10.45 g of alkyne ester monomer propynyl acrylate, 0.90 g of oxidant hydrogen peroxide, 0.30 g of reducing agent vitamin C, 0.50 g of chain transfer agent mercaptoacetic acid, and 10 mg of catalyst dichlororhodium (II) dimer;

[0046] Among them, the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer and the alkynyl ester monomer is 1:2.3:1.5;

[0047] A preparation method of a high water-reducing and high slump-retention polycarboxylate water reducer includes the following steps:

[0048] Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, 190 g of methallyl alcohol polyoxyethylene ether and 190 g of deionized water are added in sequence, and stirred and dissolved at a low speed for 20 min, and then 0.90 g of hydrogen peroxide is added to obtain a reactant solution;

[0049] Step (2): Stir and disperse 30.6 g of deionized water, 12.53 g of methacrylic acid and 9.40 g of propargyl acrylate to obtain solution A, wherein 9.40 g of propargyl acrylate is dissolved in 3 ml of N,N-dimethylformamide; Stir and dissolve 43.3 g of water, 0.50 g of mercaptoacetic acid and 0.30 g of vitamin C to obtain solution B;

[0050] Step (3): Under the condition of stirring at 20 °C, solution A and solution B are respectively added dropwise to the reactant solution in step (1). Solution A is added dropwise for 40 min, and solution B is added dropwise for 55 min. After the addition is completed, the mixture is kept warm and reacted at 40 °C for 0.5 h to obtain solution C;

[0051] Step (4): Under the condition of stirring at 30 °C, 1.05 g of propargyl acrylate and 10 mg of rhodium catalyst are added to solution C in sequence, and kept warm for 3 h to obtain a high water-reducing and high slump-retention polycarboxylate water reducer. Among them, 0.7 g of propargyl acrylate is dissolved in 0.5 ml of N,N-dimethylformamide.

[0052] Example 3

[0053] A high water-reducing and high slump-retention polycarboxylate water reducer includes 190 g of isopentenol polyoxyethylene ether as the unsaturated polyether macromonomer, 13.97 g of maleic anhydride as the unsaturated carboxylic acid monomer, 17.41 g of propargyl acrylate as the alkynyl ester monomer, 0.90 g of hydrogen peroxide as the oxidant, 0.30 g of vitamin C as the reducing agent, 0.50 g of mercaptopropionic acid as the chain transfer agent, and 26 mg of dichlorodirhodium as the catalyst;

[0054] Among them, the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer and the alkynyl ester monomer is 1:1.8:2;

[0055] A preparation method of a high water-reducing and high slump-retention polycarboxylate water reducer includes the following steps:

[0056] Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, sequentially add 190 g of isopentenol polyoxyethylene ether and 190 g of deionized water, stir and dissolve at a low speed for 20 min, and then add 0.90 g of hydrogen peroxide to obtain a reactant solution;

[0057] Step (2): Stir and disperse 30.6 g of deionized water, 13.97 g of methacrylic acid, and 14.80 g of propargyl acrylate to obtain Solution A, where 9.40 g of propargyl acrylate is dissolved in 3 ml of N,N-dimethylformamide; stir and dissolve 50.9 g of water, 0.50 g of mercaptopropionic acid, and 0.30 g of vitamin C to obtain Solution B;

[0058] Step (3): While stirring at 25 °C, dropwise add Solution A and Solution B to the reactant solution in Step (1). Solution A is added dropwise over 90 min, and Solution B is added dropwise over 120 min. After the addition is complete, keep the temperature at 40 °C and react for 1 h to obtain Solution C;

[0059] Step (4): While stirring at 30 °C, sequentially add 2.61 g of propargyl acrylate and 26 mg of rhodium catalyst to Solution C, and keep the temperature for 3 h to obtain a high water-reducing and high slump-retention polycarboxylate superplasticizer. Among them, 2.61 g of propargyl acrylate is dissolved in 0.5 ml of N,N-dimethylformamide.

[0060] Example 4

[0061] A high water-reducing and high slump-retention polycarboxylate superplasticizer, comprising 190 g of unsaturated polyether macromonomer isopentenol polyoxyethylene ether, 16.83 g of unsaturated carboxylic acid monomer, 11.3 g of alkyne ester monomer propargyl acrylate, 0.90 g of oxidant hydrogen peroxide, 0.30 g of reducing agent vitamin C, 0.50 g of chain transfer agent mercaptoethanol, and 22.6 mg of catalyst dichlorodirhodium;

[0062] Among them, the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer, and the alkyne ester monomer is 1:2.5:1.3. The unsaturated carboxylic acid monomer is a mixture of maleic anhydride and acrylic acid. The addition amount of acrylic acid is 7.13 g, and the addition amount of maleic anhydride is 9.70 g;

[0063] A preparation method of a high water-reducing and high slump-retention polycarboxylate superplasticizer, comprising the following steps:

[0064] Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, sequentially add 190 g of isopentenol polyoxyethylene ether and 190 g of deionized water, stir and dissolve at a low speed for 20 min, and then add 0.90 g of hydrogen peroxide to obtain a reactant solution;

[0065] Step (2): Stir and disperse 30.6 g of deionized water, 7.13 g of acrylic acid, 9.70 g of maleic anhydride, and 9.04 g of propargyl acrylate evenly to obtain Solution A, where 9.04 g of propargyl acrylate is dissolved in 3 ml of N,N-dimethylformamide; stir and dissolve 46.96 g of water, 0.50 g of mercaptoethanol, and 0.30 g of vitamin C to obtain Solution B.

[0066] Step (3): While stirring at 25 °C, add Solution A and Solution B dropwise to the reactant solution in Step (1). Solution A is added dropwise for 90 min, and Solution B is added dropwise for 120 min. After the addition is complete, keep the temperature at 40 °C and react for 1 h to obtain Solution C.

[0067] Step (4): While stirring at 30 °C, add 2.26 g of propargyl acrylate and 22.6 mg of rhodium catalyst to Solution C in sequence, and keep the temperature for 3 h to obtain a high water-reducing and high slump-retention polycarboxylate superplasticizer, where 2.26 g of propargyl acrylate is dissolved in 0.5 ml of N,N-dimethylformamide.

[0068] Comparative Example 1

[0069] A high water-reducing and high slump-retention polycarboxylate superplasticizer, comprising 190 g of isopentenyl alcohol polyoxyethylene ether as an unsaturated polyether macromonomer, 17.1 g of acrylic acid as an unsaturated carboxylic acid monomer, 18.37 g of hydroxyethyl acrylate as a functional ester monomer, 0.90 g of hydrogen peroxide as an oxidant, 0.30 g of vitamin C as a reducing agent, and 0.50 g of mercaptoethanol as a chain transfer agent.

[0070] Among them, the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer, and the functional ester monomer is 1:3:2.

[0071] A preparation method of a high water-reducing and high slump-retention polycarboxylate superplasticizer, comprising the following steps:

[0072] Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, add 190 g of isopentenyl alcohol polyoxyethylene ether and 190 g of deionized water in sequence, stir and dissolve at a low speed for 20 min, and then add 0.90 g of hydrogen peroxide to obtain a reactant solution.

[0073] Step (2): Stir and disperse 30.6 g of deionized water, 17.1 g of acrylic acid, and 18.37 g of hydroxyethyl acrylate evenly to obtain Solution A; stir and dissolve 57.05 g of water, 0.50 g of mercaptoethanol, and 0.30 g of vitamin C to obtain Solution B.

[0074] Step (3): Under the condition of stirring at 25°C, add solution A and solution B dropwise to the reactant solution in step (1). Solution A is added dropwise for 90 minutes, and solution B is added dropwise for 120 minutes. After the addition is completed, keep the reaction at 40°C for 1 hour to obtain a high water-reducing and high slump-retention type polycarboxylate superplasticizer.

[0075] Comparative Example 2

[0076] A high water-reducing and high slump-retention type polycarboxylate superplasticizer, comprising 190 g of unsaturated polyether macromonomer isopentenyl alcohol polyoxyethylene ether, 20.43 g of unsaturated carboxylic acid monomer methacrylic acid, 15.44 g of functional ester monomer hydroxypropyl acrylate, 0.90 g of oxidant hydrogen peroxide, 0.30 g of reducing agent vitamin C, and 0.54 g of chain transfer agent mercaptoethanol.

[0077] Among them, the molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer, and the functional ester monomer is 1:3:1.5.

[0078] A preparation method of a high water-reducing and high slump-retention type polycarboxylate superplasticizer, comprising the following steps:

[0079] Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, sequentially add 190 g of isopentenyl alcohol polyoxyethylene ether and 190 g of deionized water, stir and dissolve at a low speed for 20 minutes, and then add 0.90 g of hydrogen peroxide to obtain a reactant solution;

[0080] Step (2): Stir and disperse 30.6 g of deionized water, 20.43 g of methacrylic acid, and 15.44 g of hydroxypropyl acrylate evenly to obtain solution A; Stir and dissolve 42.49 g of water, 0.54 g of mercaptoethanol, and 0.30 g of vitamin C to obtain solution B;

[0081] Step (3): Under the condition of stirring at 25°C, add solution A and solution B dropwise to the reactant solution in step (1). Solution A is added dropwise for 90 minutes, and solution B is added dropwise for 120 minutes. After the addition is completed, keep the reaction at 40°C for 1 hour to obtain a high water-reducing and high slump-retention type polycarboxylate superplasticizer.

[0082] Comparative Example 3

[0083] The existing comprehensive polycarboxylate superplasticizer, model 3A02.

[0084] Test and detection

[0085] Perform the net paste fluidity test and concrete mix proportion test on the superplasticizers in the examples and comparative examples of the present invention. The cement paste fluidity is tested according to GB / T 8077-2000 "Test Methods for the Homogeneity of Concrete Admixtures", and the results are shown in Table 1. The cement used is Esheng Cement, and the water-cement ratio is 0.29.

[0086] The performance of the concrete was tested according to GB 8076-2008 "Concrete Admixtures". Its slump, spread, etc. were measured, and the results are shown in Table 2. The fineness modulus of the manufactured sand in the concrete was 2.8, the crushed stone was continuously graded crushed stone with a particle size of 5-25 mm, and the polycarboxylate superplasticizer had a dosage of 1.6 wt%-2.6 wt%.

[0087] Table 1: Data of the fluidity of neat cement

[0088] Sample Cement Dosage / % Initial / mm 1h / mm 2h / mm 3h / mm Example 1 Esheng Cement 0.24 180 210 230 220 Example 2 Esheng Cement 0.24 175 230 250 255 Example 3 Esheng Cement 0.24 160 220 240 235 Example 4 Esheng Cement 0.24 175 220 245 240 Comparative Example 1 Esheng Cement 0.26 180 230 235 195 Comparative Example 2 Esheng Cement 0.27 180 220 230 210 Comparative Example 3 Esheng Cement 0.28 170 225 220 170

[0089] Table 2: Concrete performance data C30

[0090]

[0091]

[0092] From the test results of the neat cement performance in Table 1 and the concrete test results in Table 2, it can be seen that the performance of the superplasticizers in Examples 1-4 is better than that of the superplasticizers in Comparative Examples 1-3. The high water-reducing and high slump-retention polycarboxylate superplasticizer provided by the present invention has a high initial water-reducing rate, good slump-retention performance, and good workability. At the same time, the high water-reducing and high slump-retention polycarboxylate superplasticizer provided by the present invention helps to reduce the sensitivity of the superplasticizer to different materials, and the strength slightly increases after being incorporated into the concrete.

[0093] Comparing the experimental results of Example 2 and Comparative Example 3 in Table 1 and Table 2, when the fluidity is close, compared with Comparative Example 3, Example 2 has a relatively lower dosage, a larger initial fluidity, and a larger fluidity at 1-3 hours, indicating that when using propynyl acrylate, the superplasticizer not only shows a better water-reducing rate, but also has a more excellent slump-retention effect, proving that propynyl acrylate can play a role in improving the water-reducing rate of the admixture and improving the slump-retention effect in the concrete.

[0094] Comparing the superplasticizer in Comparative Example 1 with the superplasticizer in Example 1, when the amount of acrylic acid is the same and at the same dosage, Comparative Example 1 shows a higher water-reducing rate and a better slump-retention effect, indicating that the water-reducing and slump-retention effects of hydroxyethyl acrylate used in Comparative Example 1 are not as good as those of propynyl acrylate in the present application, proving that propynyl acrylate in the present application has a greater impact on the performance of the superplasticizer.

[0095] Comparing the superplasticizer in Comparative Example 3 with the superplasticizer in Example 2 of the present embodiment, the fluidity performance of the cement paste and the workability of the concrete are much worse than those in Example 2.

[0096] Taking Example 2 and Comparative Example 2 as examples, by changing the dosage of the water reducer, it can be seen from the performance results that in Example 2, the state of the concrete with reduced dosage is better, the slump retention effect is good, and the paste is rich; in Comparative Example 3, with the reduced dosage, the initial state is average and the slump retention effect is poor; with the increased dosage, segregation and grabbing occur, indicating that the water reducer in Example 2 is not sensitive to the performance of concrete, while the water reducer in Comparative Example 3 is sensitive to the performance of concrete, showing that the sensitivity of Example 2 to dosage is better than that of Comparative Example 3.

[0097] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high water-reducing and high slump-retention polycarboxylate water reducer, characterized in that: It includes an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer, an alkynyl ester monomer, an oxidizing agent, a reducing agent, a chain transfer agent, and a rhodium catalyst; The molar ratio of the unsaturated polyether macromonomer, the unsaturated carboxylic acid monomer, and the alkynyl ester monomer is 1:0.5 - 3.5:0.1 - 2.

5. The dosage of the oxidizing agent is 0.1% - 1.5% of the total mass of the unsaturated polyether macromonomer. The dosage of the reducing agent is 0.1% - 2.0% of the total mass of the unsaturated polyether macromonomer. The dosage of the chain transfer agent is 0.1% - 1.2% of the total mass of the unsaturated polyether macromonomer; Part of the alkynyl ester monomer is used for olefin polymerization as an anchor point for alkynyl polymerization, and the other part is used for alkyne polymerization; The alkynyl ester monomer is propargyl acrylate; The proportion of the alkynyl ester monomer used for olefin polymerization in the alkynyl ester monomer is 70% - 90%; Part of the alkynyl ester monomer introduces a carbon-carbon triple bond into the molecular structure through free radical polymerization, providing an anchor point for alkynyl polymerization. The other part of the alkynyl ester monomer introduces a polyacetylene chain through coordination polymerization under the action of a rhodium catalyst.

2. The high water-reducing and high slump-retention polycarboxylate water reducer according to claim 1, characterized in that: The rhodium catalyst is dichlorodirhodium; 3. A high water-reducing and high slump-retention polycarboxylate superplasticizer according to claim 2, characterized in that: The dosage of the rhodium catalyst is 0.1% - 5% of the weight of the alkynyl ester monomer used for alkyne polymerization; 4. The high water-reducing and high slump-retention polycarboxylate water reducer according to claim 1, wherein: The unsaturated polyether macromonomer is at least one of isopentenol polyoxyethylene ether, isobutenol polyoxyethylene ether, and methallyl alcohol polyoxyethylene ether; 5. The high water-reducing and high slump-retention polycarboxylate water-reducing agent according to claim 1, characterized in that: The unsaturated carboxylic acid monomer is at least one of acrylic acid, methacrylic acid, and maleic anhydride; 6. The high water-reducing and high slump-retention polycarboxylate water-reducing agent according to claim 1, characterized in that: The oxidizing agent is at least one of ammonium persulfate, sodium persulfate, potassium persulfate, and hydrogen peroxide; the reducing agent is at least one of vitamin C, ferrous sulfate, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium hypophosphite, sodium formaldehyde sulfoxylate, and sodium dithionite; the chain transfer agent is at least one of mercaptoacetic acid, mercaptoethanol, mercaptopropionic acid, and aliphatic mercaptan.

7. A preparation method of a high water-reducing and high slump-retention polycarboxylate water reducer, which is used to prepare the high water-reducing and high slump-retention polycarboxylate water reducer described in any one of claims 1-6, characterized in that, It includes the following steps: Step (1): In a glass reactor equipped with a thermometer and a mechanical stirrer, sequentially add the unsaturated polyether macromonomer and water, stir at a low speed, and then add the oxidizing agent to obtain a reactant solution; Step (2): Dissolve the unsaturated carboxylic acid monomer and part of the alkynyl ester monomer used for olefin polymerization as an anchor point for alkynyl polymerization in water, and stir and disperse evenly to obtain solution A; dissolve the reducing agent and the chain transfer agent in water, and stir and dissolve to obtain solution B; Step (3): Under stirring at 10°C - 60°C, respectively drip solution A and solution B into the reactant solution in step (1). Solution A is dripped for 30 min - 180 min, and solution B is dripped for 30 min - 180 min. After dripping, keep the temperature at 20°C - 40°C and carry out a heat preservation reaction for 0.5 h - 2.5 h to obtain solution C; Step (4): Under stirring at 10°C - 60°C, add the other part of the alkynyl ester monomer used for alkyne polymerization and the rhodium catalyst to solution C, and keep the temperature for 3 h to obtain a high water-reducing and high slump-retention polycarboxylate superplasticizer.

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