Viscosity-reducing polycarboxylic superplasticizer and preparation method therefor

Abstract

Disclosed are a viscosity-reducing polycarboxylic superplasticizer and a preparation method therefor. The viscosity-reducing polycarboxylic superplasticizer is obtained by compounding a macromolecular polymer and a pre-wrapped small-molecule polymer in a weight ratio of 1.7-2.3 : 1, wherein the molecular weight of the macromolecular polymer is between 75,000-85,000; and the pre-wrapped small-molecule polymer comprises a small-molecule polymer, a thickening agent and water in a weight ratio of 1,000 : 0.7-1.3 : 8-10, with the molecular weight of the small-molecule polymer being between 14,000-16,000. The polycarboxylic superplasticizer is prepared by compounding the macromolecular polymer and the small-molecule polymer in a certain proportion, thereby exerting a linked viscosity reduction effect, effectively reducing the slurry viscosity of high-performance concrete, improving the adaptability of a concrete admixture, and solving the problem of the site construction of high-performance concrete being difficult.

Description

A viscosity-reducing polycarboxylate superplasticizer and its preparation method Technical Field

[0001] This application relates to the technical field of water-reducing agents, specifically to a viscosity-reducing polycarboxylate water-reducing agent and its preparation method. Background Technology

[0002] With the rapid development of my country's construction and infrastructure industry, highway, railway, bridge, tunnel and high-rise building projects are increasing. Polycarboxylate superplasticizers are widely used in high-performance concrete due to their high strength and good workability. In practical applications, to improve concrete strength, measures such as using high-strength cement, increasing the amount of cementitious materials, and reducing the water-cement ratio are usually adopted. At the same time, the advancement of cement production technology has made cement finer, increasing the water demand of cement. These factors will lead to an increase in concrete viscosity, a slower flow rate, increased construction difficulty and reduced construction efficiency, which greatly limits the application of high-performance concrete.

[0003] Currently, common methods for reducing concrete viscosity include increasing the dosage of water-reducing agents, optimizing the particle size distribution of binders, and compounding air-entraining agents and viscosity-reducing agents. However, when dealing with high-performance concrete, technicians often encounter problems such as segregation and peeling due to increased water-reducing agent dosage; the inability to adjust or significantly optimize on-site raw materials and concrete mix proportions; poor adaptability of air-entraining agents due to the complexity and diversity of concrete raw materials, which can negatively impact concrete strength; and the insignificant viscosity-reducing effect of viscosity-reducing agents, which cannot improve excessive concrete viscosity.

[0004] With the increasing prominence of concrete viscosity issues, the development of viscosity-reducing polycarboxylate superplasticizers has become a research hotspot in recent years. Viscosity-reducing superplasticizers can release free water from the pore fluid in concrete, thereby achieving the effect of reducing viscosity. However, the reduction of the surface tension of the paste can easily lead to an increase in air content, affecting the mechanical properties of concrete and other problems.

[0005] Therefore, it is of great significance to develop a low molecular weight polycarboxylate superplasticizer that can effectively reduce viscosity, has no adverse effect on the mechanical properties of concrete, and improves the workability of concrete. It can effectively avoid the limitations and adaptability of effective viscosity reduction effects caused by compound viscosity reducing agents, and has broad application prospects in high-strength, high-grade self-compacting and other high-performance concretes. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a viscosity-reducing polycarboxylate superplasticizer and its preparation method.

[0007] This application provides a viscosity-reducing polycarboxylate superplasticizer, which is obtained by compounding a macromolecular polymer and a pre-coated small molecule polymer in a weight ratio of 1.7-2.3:1.

[0008] The macromolecular polymer specifically comprises the following components in parts by weight:

[0009] The composition includes 280-380 parts of ether macromonomers; 10-25 parts of benzene ring functional monomers; 28-45 parts of unsaturated acids; 0.8-1.8 parts of reducing agents; 3-6 parts of chain transfer agents; 2.7-3.8 parts of oxidizing agents; and water; wherein the molecular weight of the macromolecular polymer is between 75,000 and 85,000.

[0010] The pre-coated small molecule polymer comprises a small molecule polymer, a thickener, and water in a weight ratio of 1000:0.7-1.3:8-10; the small molecule polymer specifically comprises the following components in parts by weight:

[0011] The composition includes: 200-300 parts of ether macromonomers; 50-100 parts of viscosity-reducing ether macromonomers; 8-18 parts of functional monomers; 25-40 parts of unsaturated acids; 0.5-1.4 parts of reducing agents; 2.2-6.8 parts of chain transfer agents; 2.8-4.2 parts of oxidizing agents; and water; wherein the molecular weight of the small molecule polymer is between 14,000 and 16,000.

[0012] The thickener is selected from sodium polyacrylate with a molecular weight of 10,000 or carboxymethyl cellulose with a molecular weight of 10,000.

[0013] Preferably, the viscosity-reducing polycarboxylate superplasticizer is obtained by compounding a macromolecular polymer and a pre-coated small molecule polymer in a weight ratio of 1.9-2.1:1.

[0014] Preferably, the pre-coated small molecule polymer comprises a small molecule polymer, a thickener, and water in a weight ratio of 1000:0.9-1.1:8.5-9.5.

[0015] Preferably, the molecular weight of the ether macromonomer is 2400 or 3000, and the ether macromonomer is selected from one or more of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, propylene alcohol polyoxyethylene ether, allyl polyethylene glycol, methoxy polyethylene glycol ether, and ethyleneoxy polyethylene glycol ether; the molecular weight of the viscosity-reducing ether macromonomer is 600 or 1200, and the viscosity-reducing ether macromonomer is selected from one or more of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, propylene alcohol polyoxyethylene ether, allyl polyethylene glycol, methoxy polyethylene glycol ether, and ethyleneoxy polyethylene glycol ether.

[0016] Preferably, the benzene ring functional monomer is selected from one or more of ferulic acid, styrene, 1-allyl-4-fluorobenzene, 1-phenylvinylboronic acid, and 4-methoxy-2-vinylaniline.

[0017] Preferably, the functional monomer is selected from one or more of methyl acrylate, methyl methacrylate, propyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate phosphate, and ammonium acrylate.

[0018] Preferably, the unsaturated acid is selected from one or more of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid.

[0019] Preferably, the reducing agent is selected from one or more of sodium sulfite, sodium bisulfite, ascorbic acid, ferrous sulfate, sodium hypophosphite, sodium formaldehyde sulfoxylate, and E51.

[0020] Preferably, the chain transfer agent is selected from one or more of mercaptoacetic acid, mercaptopropionic acid, sodium hypophosphite, mercaptoethanol, and dodecyl mercaptan.

[0021] Preferably, the oxidant is selected from one or more of potassium persulfate, sodium bisulfite, ammonium persulfate, hydrogen peroxide, and tert-butylhydroperoxide.

[0022] Preferably, the thickener is selected from one or more of acrylic acid monomers, pentaerythritol cross-linked copolymers, carboxymethyl cellulose, and water-soluble sodium polyacrylate with a molecular weight of 2000-50000.

[0023] Secondly, this application provides a method for preparing the above-mentioned viscosity-reducing polycarboxylate superplasticizer, specifically including the following steps:

[0024] (1) Synthesis of macromolecular polymers: Add the bottom raw materials to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B;

[0025] (1.1) Add the bottom material to the four-necked flask: add ether macromonomer, deionized water and 10-25% of unsaturated acid;

[0026] (1.2) Preparation of each component of material A: Add the remaining unsaturated acid, benzene ring monomer, and deionized water, and stir thoroughly;

[0027] (1.3) Preparation of each component of material B: Add reducing agent, chain transfer agent, and deionized water, and stir thoroughly;

[0028] (1.4) Place the four-necked flask into the water bath, turn on the stirrer to stir the material evenly, and set the ambient temperature to 20-40℃.

[0029] After stirring evenly, add the oxidant to the four-necked flask while stirring, and continue stirring for 5-10 minutes.

[0030] While stirring, start adding component A and component B simultaneously. Component A should be added for 80-120 minutes, and component B for 90-140 minutes.

[0031] Maintain the temperature at the end of the dropping process for 50-150 minutes.

[0032] After the heat preservation is completed, deionized water is added for dilution and stirred until uniform to obtain a macromolecular polymer with a molecular weight between 75,000 and 85,000.

[0033] (2) Synthesis of small molecule polymers: Add the bottom raw materials to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B;

[0034] (2.1) Add the bottom material to the four-necked flask: add ether macromonomers and viscosity-reducing ether macromonomers, deionized water and 10-25% of unsaturated acid;

[0035] (2.2) Preparation of each component of material A: Add the remaining unsaturated acid, functional monomer, and deionized water, and stir thoroughly;

[0036] (2.3) Preparation of each component of material B: Add reducing agent, chain transfer agent, and deionized water, and stir thoroughly;

[0037] (2.4) Place the four-necked flask into the water bath, turn on the stirrer to stir the material evenly, and set the ambient temperature to 20-40℃.

[0038] After stirring evenly, add the oxidizing agent or reducing agent to the four-necked flask while stirring, and continue stirring for 5-10 minutes.

[0039] While stirring, start adding component A and component B simultaneously. Component A should be added for 80-120 minutes, and component B for 90-140 minutes.

[0040] Maintain the temperature at the end of the dropping process for 50-150 minutes.

[0041] After the heat preservation is completed, add deionized water to dilute and stir until uniform to obtain a small molecule polymer with a molecular weight between 14,000 and 16,000.

[0042] (3) Preparation of pre-coated small molecule polymers:

[0043] The thickener is dissolved in deionized water, and after complete dissolution, it is added to the small molecule polymer and stirred thoroughly to obtain the final product.

[0044] (4) The macromolecular polymer and the pre-coated small molecule polymer are compounded and premixed in proportion and stirred until completely mixed to obtain the final product.

[0045] This application provides a viscosity-reducing polycarboxylate superplasticizer and its preparation method, which effectively reduces the viscosity of high-performance concrete paste, improves the adaptability of concrete admixtures, and solves the problem of difficult on-site construction of high-performance concrete. The preparation process first uses a combination of multiple macromonomers with different molecular weights. By adjusting the concentration of the initiation system, the acid-ether ratio, the chain transfer agent, the type and dosage of functional monomers, and the initial reaction temperature, a macromolecular polymer and a small molecule polymer that can effectively reduce the viscosity of concrete paste are obtained. Next, the small molecule polymer is premixed with a thickener. Finally, the two polymers are compounded in a certain proportion for use, which has a significant effect on reducing the viscosity of concrete.

[0046] The viscosity-reducing polycarboxylate superplasticizer prepared in this application is produced in a green and environmentally friendly process. The molecular weight of the macromolecular polymer is controlled between 75,000 and 85,000, and the molecular weight of the small molecule polymer is controlled between 14,000 and 16,000. Through the design and optimization of the molecular structure of the polycarboxylate superplasticizer, the macromolecular polymer increases the hydrophilicity of PCE (polycarboxylate superplasticizer) to reduce the plastic viscosity of cement paste. By adjusting the thickness of the water film layer around the particles, the dispersibility is improved and the lubrication between particles is increased. The small molecule polymer is released after the thickener is hydrolyzed by alkali, which can play an auxiliary role in dispersion and lubrication. Under the combined effect, the viscosity of concrete paste can be effectively reduced without adversely affecting the concrete density and mechanical properties, and the workability of concrete can be improved.

[0047] In summary, the technical solution of this application has the following effects:

[0048] The viscosity-reducing polycarboxylate superplasticizer described in this application is prepared by compounding macromolecular polymers and small molecule polymers in a certain proportion, thereby exerting a synergistic viscosity-reducing effect.

[0049] During the polymerization process, benzene ring groups are added to macromolecular polymers. The grafted benzene ring groups increase the polarity of the polymer, lock in more free water, increase the thickness of the water film layer, and the increase in polarity increases the steric hindrance between molecules, resulting in better dispersion performance and a decrease in concrete viscosity.

[0050] Small molecule polymers, through the design of their molecular structure, ensure sufficient electrostatic repulsion and steric hindrance while controlling their molecular weight between 14,000 and 16,000. In the pore solution of cement slurry, they play an auxiliary dispersing role, which helps disperse cement particles without affecting the normal adsorption of PCE. They can dissolve in the pore solution to provide lubrication between particles and reduce friction, thereby achieving a viscosity reduction effect.

[0051] The small molecule polymer is pre-coated with a thickener and then compounded with the large molecule polymer in a certain proportion. When the viscosity-reducing water-reducing agent is added to the concrete, the large molecule polymer is normally adsorbed and dispersed to reduce viscosity. Furthermore, the sodium polyacrylate coated on the outside of the small molecule polymer hydrolyzes in the alkaline environment of the cement paste, releasing the small molecule polymer. The small molecule polymer dissolves in the pore solution and provides a lubricating effect. Both aspects work together to reduce the viscosity of the concrete. Detailed Implementation

[0052] The present application will be further described in detail below with reference to embodiments, comparative examples and performance test results. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0053] Example

[0054] Example 1

[0055] Example 1 provides a viscosity-reducing polycarboxylate superplasticizer.

[0056] The types of raw materials in Example 1 are shown below.

[0057] Macromolecular polymer raw materials: Ether macromonomers: HPEG (2400) is used; Benzene ring functional monomers: 4-methoxy-2-vinylaniline is used; Unsaturated acid: Acrylic acid; Reducing agent: Vitamin C is used; Oxidizing agent: Hydrogen peroxide is used; Chain transfer agent: Mercaptopropionic acid is used.

[0058] Small molecule polymer raw materials: Ether macromonomers: HPEG (2400), viscosity-reducing ether macromonomers: APEG (600), unsaturated acids: acrylic acid, functional monomers: methyl acrylate, reducing agent: vitamin C, oxidizing agent: hydrogen peroxide, chain transfer agent: mercaptopropionic acid.

[0059] Pre-coated thickener: Sodium polyacrylate (10000).

[0060] The amount of each raw material used in Example 1 is shown in Table 1.

[0061] Table 1. Amounts of each raw material used in Example 1

[0062] The specific preparation method of the viscosity-reducing polycarboxylate superplasticizer in Example 1 is shown below.

[0063] (1) Synthesis of macromolecular polymers: Add the bottom raw materials to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B;

[0064] (1.1) Add the bottom material to the four-necked flask: add ether macromonomer, deionized water and some unsaturated acid acrylic acid;

[0065] (1.2) Preparation of each component of material A: Add all remaining unsaturated acid acrylic acid, benzene ring monomer, and deionized water, and stir thoroughly;

[0066] (1.3) Preparation of each component of material B: Add reducing agent, chain transfer agent mercaptopropionic acid, and deionized water, and stir thoroughly;

[0067] (1.4) Place the four-necked flask into the water bath, turn on the stirrer to stir the material evenly, and set the ambient temperature to 35℃.

[0068] After stirring evenly, add the oxidant to the four-necked flask while stirring, and continue stirring for 5-10 minutes.

[0069] While stirring, start adding material A and material B simultaneously. Material A is added for 120 minutes, and material B is added for 135 minutes.

[0070] Maintain the temperature at the end of the dropping process for 60 minutes.

[0071] After the heat preservation is completed, deionized water is added for dilution and stirred until uniform to obtain a macromolecular polymer with a molecular weight between 75,000 and 85,000.

[0072] (2) Synthesis of small molecule polymers: Add the bottom raw materials to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B;

[0073] (2.1) Add the bottom material to the four-necked flask: add macromonomer, deionized water, APEG and some acrylic acid;

[0074] (2.2) Preparation of each component of material A: Add all remaining acrylic acid, methyl acrylate, and deionized water, and stir thoroughly;

[0075] (2.3) Preparation of each component of material B: Add vitamin C, chain transfer agent mercaptopropionic acid, and deionized water, and stir thoroughly;

[0076] (2.4) Place the four-necked flask in a room temperature environment and turn on the stirrer to mix the materials evenly. The ambient temperature is about 20°C.

[0077] After mixing thoroughly, add hydrogen peroxide to the four-necked flask and continue stirring for 5-10 minutes.

[0078] While stirring, start adding material A and material B simultaneously. Material A is added for 110 minutes, and material B is added for 130 minutes.

[0079] Maintain the temperature at the end of the dripping process for 60 minutes.

[0080] After the heat preservation is completed, add deionized water to dilute and stir until uniform to obtain a small molecule polymer with a molecular weight between 14,000 and 16,000.

[0081] (3) Preparation of pre-coated small molecule polymers:

[0082] The weight ratio of small molecule polymer, thickener, and water is 1000:1:9; dissolve the thickener in deionized water, and then add it to the small molecule polymer. Stir thoroughly to mix evenly to obtain the final product.

[0083] (4) Premix the macromolecular polymer and the pre-coated small molecule polymer:

[0084] Extract materials into a mixing tank or compounding vessel at a 1:1 ratio of macromolecular polymer and pretreated small molecule polymer, and stir evenly to obtain the final product.

[0085] Example 2

[0086] Example 2 provides a viscosity-reducing polycarboxylate superplasticizer.

[0087] The types of raw materials in Example 2 are shown below.

[0088] Macromolecular polymer raw materials: Ether macromonomers: HPEG (2400) is used; Benzene ring functional monomers: Styrene is used; Unsaturated acid: Acrylic acid; Reducing agent: Vitamin C is used; Oxidizing agent: Hydrogen peroxide is used; Chain transfer agent: Mercaptopropionic acid is used.

[0089] Small molecule polymer raw materials: Ether macromonomers: HPEG (2400), viscosity-reducing ether macromonomers: APEG (1200), unsaturated acid: acrylic acid, functional monomers: hydroxypropyl acrylate, reducing agent: vitamin C, oxidizing agent: hydrogen peroxide, chain transfer agent: mercaptopropionic acid.

[0090] Pre-coated thickener: carboxymethyl cellulose (10000).

[0091] The amount of each raw material used in Example 2 is shown in Table 2.

[0092] Table 2. Amounts of each raw material used in Example 2

[0093] The preparation method of the viscosity-reducing polycarboxylate superplasticizer in Example 2 is as follows.

[0094] (1) Add the bottom raw material of the macromolecular polymer to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B;

[0095] (1.1) Add the bottom material to the four-necked flask: add macromonomer, deionized water and some acrylic acid;

[0096] (1.2) Preparation of each component of material A: Add all remaining acrylic acid, styrene, and deionized water, and stir thoroughly;

[0097] (1.3) Preparation of each component of material B: Add reducing agent and deionized water, and stir thoroughly;

[0098] (1.4) Place the four-necked flask in a water bath, turn on the stirrer to mix the materials evenly, and set the water bath temperature to about 40°C.

[0099] After mixing thoroughly, add hydrogen peroxide to the four-necked flask and continue stirring for 5-10 minutes.

[0100] While stirring, start adding material A and material B simultaneously. Material A is added for 120 minutes, and material B is added for 132 minutes.

[0101] Maintain the temperature at the end of the dripping process for 60 minutes.

[0102] After the heat preservation is completed, deionized water is added for dilution and stirred until uniform to obtain a macromolecular polymer with a molecular weight between 75,000 and 85,000.

[0103] (2) Synthesis of small molecule polymers: Add the bottom raw materials to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B;

[0104] (2.1) Add the bottom material to the four-necked flask: add macromonomer, deionized water, APEG and some acrylic acid;

[0105] (2.2) Preparation of each component of material A: Add all remaining acrylic acid, hydroxypropyl acrylate, and deionized water, and stir thoroughly;

[0106] (2.3) Preparation of each component of material B: Add vitamin C, mercaptopropionic acid, and deionized water, and stir thoroughly;

[0107] (2.4) Place the four-necked flask in a room temperature environment and turn on the stirrer to mix the materials evenly. The ambient temperature is about 20°C.

[0108] After mixing thoroughly, add hydrogen peroxide to the four-necked flask and continue stirring for 5-10 minutes.

[0109] While stirring, start adding material A and material B simultaneously. Material A is added for 120 minutes, and material B is added for 132 minutes.

[0110] Maintain the temperature at the end of the dripping process for 60 minutes.

[0111] After the heat preservation is completed, deionized water is added for dilution and stirred until uniform to obtain a small molecule polymer with a molecular weight between 14,000 and 16,000.

[0112] (3) Preparation of pre-coated small molecule polymers:

[0113] The weight ratio of small molecule polymer, thickener, and water is 1000:1:9; dissolve the thickener in deionized water, and then add it to the small molecule polymer. Stir thoroughly to mix evenly to obtain the final product.

[0114] (4) Mix the macromolecular polymer and the pre-coated small molecule polymer in a 2:1 ratio and stir until homogeneous.

[0115] Examples 3-4

[0116] Examples 3-4 provide a viscosity-reducing polycarboxylate superplasticizer.

[0117] The difference between the above embodiments and Embodiment 2 lies in the ratio of macromolecular polymer and pre-coated small molecule polymer.

[0118] In Example 3, the weight ratio of macromolecular polymer to pre-coated small molecule polymer was 1.7:1.

[0119] In Example 4, the weight ratio of macromolecular polymer to pre-coated small molecule polymer was 2.3:1.

[0120] The remaining steps of the above embodiments are the same as those of Embodiment 2.

[0121] Examples 5-6

[0122] Examples 5-6 respectively provide a viscosity-reducing polycarboxylate superplasticizer.

[0123] The difference between the above embodiment and Embodiment 2 is that the weight ratio of small molecule polymer, thickener and water in the pre-coated small molecule polymer is different.

[0124] In Example 5, the weight ratio of the small molecule polymer, thickener, and water was 1000:0.7:8.

[0125] In Example 6, the weight ratio of small molecule polymer, thickener, and water was 1000:1.3:10.

[0126] The remaining steps of the above embodiments are the same as those of Embodiment 2.

[0127] Comparative Example

[0128] Comparative Example 1

[0129] This comparative example provides a water-reducing agent.

[0130] Commercially available viscosity-reducing polycarboxylate superplasticizer mother liquor, with a solid content of 40%.

[0131] Comparative Example 2

[0132] This comparative example provides a water-reducing agent.

[0133] The types of raw materials used in this comparative example are shown below.

[0134] Ether macromonomers: HPEG (2400) was used; benzene ring macromonomers: 4-methoxy-2-vinylaniline was used; unsaturated acid: methacrylic acid; reducing agent: E51 was used; oxidizing agent: hydrogen peroxide was used; chain transfer agent: sodium hypophosphite was used.

[0135] The amount of each raw material used in this comparative example is shown in Table 3.

[0136] Table 3 shows the usage of each raw material in Comparative Example 2.

[0137] The specific preparation method of the viscosity-reducing polycarboxylate superplasticizer in this comparative example is shown below.

[0138] Add the bottom ingredients to the four-necked flask according to the proportions, prepare the components of ingredient A, and prepare the components of ingredient B;

[0139] (1) Add the bottom material to the four-necked flask: add macromonomer, deionized water, chain transfer agent and some methacrylic acid;

[0140] (2) Prepare the components of material A: Add all remaining methacrylic acid, benzene ring functional monomers, and deionized water, and stir thoroughly;

[0141] (3) Prepare the components of material B: Add E51 and deionized water, and stir thoroughly;

[0142] (4) Place the four-necked flask in a room temperature environment and turn on the stirrer to mix the materials evenly. The ambient temperature is about 20°C. After mixing evenly, add hydrogen peroxide to the four-necked flask and continue stirring for 5-10 minutes.

[0143] While stirring, start adding material A and material B simultaneously. Material A is added for 90 minutes, and material B is added for 110 minutes.

[0144] Maintain the temperature at the end of the dripping process for 60 minutes.

[0145] After the heat preservation is completed, deionized water is added for dilution and stirred until uniform to obtain a macromolecular polymer with a molecular weight between 75,000 and 85,000; this polymer can be used as a water-reducing agent.

[0146] Comparative Example 3

[0147] This comparative example provides a water-reducing agent.

[0148] The types of raw materials used in this comparative example are shown below.

[0149] Ether macromonomers: GPEG (3000) was used; viscosity-reducing ether macromonomers: methoxy polyethylene glycol ether was used; unsaturated acid: acrylic acid; functional monomers: acrylamide was used; reducing agent: E51 was used; oxidizing agent: hydrogen peroxide was used; chain transfer agent: mercaptoethanol was used.

[0150] The amount of each raw material used in this comparative example is shown in Table 4.

[0151] Table 4 shows the usage of each raw material in Comparative Example 3.

[0152] The specific preparation method of the viscosity-reducing polycarboxylate superplasticizer in this comparative example is shown below.

[0153] Add the bottom ingredients to the four-necked flask according to the proportions, prepare the components of ingredient A, and prepare the components of ingredient B;

[0154] (1) Add the bottom material to the four-necked flask: add macromonomer, deionized water, acrylamide and viscosity-reducing ether macromonomer;

[0155] (2) Prepare the components of material A: Add acrylic acid and deionized water, and stir thoroughly;

[0156] (3) Prepare the components of material B: Add E51, mercaptoethanol, and deionized water, and stir thoroughly;

[0157] (4) Place the four-necked flask in a water bath environment, turn on the stirrer to stir the material evenly, and set the water bath environment temperature to about 30°C.

[0158] After mixing thoroughly, add hydrogen peroxide to the four-necked flask and continue stirring for 5-10 minutes.

[0159] While stirring, start adding material A and material B simultaneously. Material A is added for 100 minutes, and material B is added for 125 minutes.

[0160] Maintain the temperature at the end of the dripping process for 75 minutes.

[0161] After the heat preservation is completed, deionized water is added for dilution and stirred until uniform to obtain a small molecule polymer with a molecular weight between 14,000 and 16,000; this can be used as a water-reducing agent.

[0162] Comparative Example 4

[0163] This comparative example provides a water-reducing agent (a common water-reducing polycarboxylate water-reducing agent).

[0164] The types of raw materials used in this comparative example are shown below.

[0165] Ether macromonomers: GPEG (3000) was used; unsaturated acids: acrylic acid was used; reducing agent: vitamin C was used; oxidizing agent: hydrogen peroxide was used; chain transfer agent: sodium hypophosphite was used.

[0166] The amount of each raw material used in this comparative example is shown in Table 5.

[0167] Table 5 shows the usage of each raw material in Comparative Example 4.

[0168] The specific preparation method of the viscosity-reducing polycarboxylate superplasticizer in this comparative example is shown below.

[0169] Add the bottom ingredients to the four-necked flask according to the proportions, prepare the components of ingredient A, and prepare the components of ingredient B;

[0170] (1) Add the bottom material to the four-necked flask: add hexane monomer, deionized water and some acrylic acid;

[0171] (2) Prepare the components of material A: Add all remaining acrylic acid, functional monomers, and deionized water, and stir thoroughly;

[0172] (3) Prepare the components of material B: Add reducing agent, deionized water, and sodium hypophosphite, and stir thoroughly;

[0173] (4) Place the four-necked flask into a negative temperature water bath, turn on the stirrer to stir the material evenly, and set the ambient temperature to 10℃.

[0174] After mixing thoroughly, add hydrogen peroxide to the four-necked flask and continue stirring for 5-10 minutes.

[0175] While stirring, start adding material A and material B simultaneously. Material A is added for 45 minutes, and material B is added for 55 minutes.

[0176] Maintain the temperature at the end of the dripping process for 60 minutes.

[0177] After the heat preservation is complete, add deionized water to dilute and stir until uniform.

[0178] Performance testing

[0179] Comparative tests were conducted on the prepared water-reducing agents and cement pastes.

[0180] Test Condition 1: According to GB / T8077-2012 "Test Method for Homogeneity of Concrete Admixtures", the cement paste reference cement is 600g, the designed water-cement ratio is 0.20, the water is 120g (the water in the water-reducing agent needs to be deducted), and the water-reducing agent dosage is set to 0.45%. The fluidity of the prepared water-reducing paste and the Marsh emptying time of the paste are tested respectively.

[0181] The Marsh emptying time test uses a standard inverted conical funnel. The experiment is designed such that after 250ml of cement slurry is placed in each funnel, the timing starts at the same time the bottom valve is opened, and the time taken for the slurry to be completely emptied is measured to evaluate the differences in viscosity reduction performance of each group of water-reducing agents.

[0182] Test results are shown in Table 6.

[0183] As shown in the table, the flowability of each group is within the range of 260±5mm. Under the same initial flowability, the Marsh viscosity-reducing polycarboxylate superplasticizer prepared in Example 2 has a fast emptying time and excellent viscosity-reducing performance of the mother liquor.

[0184] Test Condition 2: According to GB / T8077-2012 "Test Method for Homogeneity of Concrete Admixtures", the cement paste reference cement is 600g, the designed water-cement ratio is 0.18, the water is 108g (the water in the water-reducing agent needs to be deducted), and the water-reducing agent dosage is set to 0.55%. The fluidity of the prepared water-reducing paste and the Marsh emptying time of the paste are tested respectively.

[0185] The Marsh emptying time test uses a standard inverted conical funnel. The experiment is designed such that after 250ml of cement slurry is placed in each funnel, the timing starts at the same time the bottom valve is opened, and the time taken for the slurry to be completely emptied is measured to evaluate the differences in viscosity reduction performance of each group of water-reducing agents.

[0186] The experimental results are shown in Table 6 below;

[0187] As shown in the table, after reducing the water-cement ratio to 0.18 and increasing the folded solid content, the flowability of each group was within the range of 260±5mm. Under the same initial flowability, the viscosity-reducing polycarboxylate superplasticizer Marsh prepared in Example 2 had a fast emptying time and excellent viscosity-reducing performance of the mother liquor.

[0188] Test Condition 3: According to GB / T8077-2012 "Test Method for Homogeneity of Concrete Admixtures", the cement paste reference cement is 600g, the designed water-cement ratio is 0.16, the water is 96g (the water in the water-reducing agent needs to be deducted), and the water-reducing agent dosage is set to 0.70%. The fluidity of the prepared water-reducing paste and the Marsh emptying time of the paste are tested respectively.

[0189] The Marsh emptying time test uses a standard inverted conical funnel. The experiment is designed such that after 250ml of cement slurry is placed in each funnel, the timing starts at the same time the bottom valve is opened, and the time taken for the slurry to be completely emptied is measured to evaluate the differences in viscosity reduction performance of each group of water-reducing agents.

[0190] The experimental results are shown in Table 6 below;

[0191] As shown in the table, after reducing the water-cement ratio to 0.16 and increasing the folded solids content to 0.70%, the flowability of each group was within the range of 260±5mm. Under the same initial flowability, the viscosity-reducing polycarboxylate superplasticizer Marsh prepared in Example 2 had a fast emptying time and excellent viscosity-reducing performance of the mother liquor.

[0192] Table 6. Performance test results of water-reducing agents in the examples and comparative examples.

[0193] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A viscosity-reducing polycarboxylate superplasticizer, characterized in that, The viscosity-reducing polycarboxylate superplasticizer is obtained by compounding a macromolecular polymer and a pre-coated small molecule polymer in a weight ratio of 1.7-2.3:

1. The macromolecular polymer specifically comprises the following components in parts by weight: The composition comprises: 280-380 parts of ether macromonomers; 10-25 parts of benzene ring functional monomers; 28-45 parts of unsaturated acids; 0.8-1.8 parts of reducing agents; 3-6 parts of chain transfer agents; 2.7-3.8 parts of oxidizing agents; and water; wherein the molecular weight of the macromolecular polymer is between 75,000 and 85,000; wherein the molecular weight of the ether macromonomers is 2,400 or 3,000; and wherein the benzene ring functional monomers are selected from one or more of ferulic acid, styrene, 1-allyl-4-fluorobenzene, 1-phenylvinylboronic acid, and 4-methoxy-2-vinylaniline. The pre-coated small molecule polymer comprises a small molecule polymer, a thickener, and water in a weight ratio of 1000:0.7-1.3:8-10; the small molecule polymer specifically comprises the following components in parts by weight: The composition includes: 200-300 parts of ether macromonomers; 50-100 parts of viscosity-reducing ether macromonomers; 8-18 parts of functional monomers; 25-40 parts of unsaturated acids; 0.5-1.4 parts of reducing agents; 2.2-6.8 parts of chain transfer agents; 2.8-4.2 parts of oxidizing agents; and water; wherein the molecular weight of the small molecule polymer is between 14,000 and 16,000; the molecular weight of the ether macromonomers is 2,400 or 3,000; the molecular weight of the viscosity-reducing ether macromonomers is 600 or 1,200; and the functional monomers are selected from one or more of methyl acrylate, methyl methacrylate, propyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate phosphate, and ammonium acrylate. The thickener is selected from sodium polyacrylate with a molecular weight of 10,000 or carboxymethyl cellulose with a molecular weight of 10,000.

2. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The ether macromonomers are selected from one or more of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, propylene alcohol polyoxyethylene ether, allyl polyethylene glycol, methoxy polyethylene glycol ether, and ethyleneoxy polyethylene glycol ether; the viscosity-reducing ether macromonomers are selected from one or more of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, propylene alcohol polyoxyethylene ether, allyl polyethylene glycol, methoxy polyethylene glycol ether, and ethyleneoxy polyethylene glycol ether.

3. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The unsaturated acid is selected from one or more of acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and fumaric acid.

4. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The reducing agent is selected from one or more of sodium sulfite, sodium bisulfite, ascorbic acid, ferrous sulfate, sodium hypophosphite, sodium formaldehyde sulfoxylate, and E51.

5. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The chain transfer agent is selected from one or more of mercaptoacetic acid, mercaptopropionic acid, sodium hypophosphite, mercaptoethanol, and dodecyl mercaptan.

6. The viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The oxidant is selected from one or more of potassium persulfate, sodium bisulfite, ammonium persulfate, hydrogen peroxide, and tert-butylhydroperoxide.

7. The method for preparing the viscosity-reducing polycarboxylate superplasticizer according to any one of claims 1-6, characterized in that, Specifically, the following steps are included: (1) Synthesis of macromolecular polymers: Add the bottom raw materials to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B; (1.1) Add the bottom material to the four-necked flask: add ether macromonomer, deionized water and 10-25% of unsaturated acid; (1.2) Preparation of each component of material A: Add the remaining unsaturated acid, benzene ring monomer, and deionized water, and stir thoroughly; (1.3) Preparation of each component of material B: Add reducing agent, chain transfer agent, and deionized water, and stir thoroughly; (1.4) Place the four-necked flask into the water bath, turn on the stirrer to stir the material evenly, and set the ambient temperature to 20-40℃. After stirring evenly, add the oxidant to the four-necked flask while stirring, and continue stirring for 5-10 minutes. While stirring, start adding component A and component B simultaneously. Component A should be added for 80-120 minutes, and component B for 90-140 minutes. Maintain the temperature at the end of the dropping process for 50-150 minutes. After the heat preservation is completed, deionized water is added for dilution and stirred until uniform to obtain a macromolecular polymer with a molecular weight between 75,000 and 85,000. (2) Synthesis of small molecule polymers: Add the bottom raw materials to the four-necked flask according to the ratio, prepare the components of material A, and prepare the components of material B; (2.1) Add the bottom material to the four-necked flask: add ether macromonomers and viscosity-reducing ether macromonomers, deionized water and 10-25% of unsaturated acid; (2.2) Preparation of each component of material A: Add the remaining unsaturated acid, functional monomer, and deionized water, and stir thoroughly; (2.3) Preparation of each component of material B: Add reducing agent, chain transfer agent, and deionized water, and stir thoroughly; (2.4) Place the four-necked flask into the water bath, turn on the stirrer to stir the material evenly, and set the ambient temperature to 20-40℃. After stirring evenly, add the oxidizing agent or reducing agent to the four-necked flask while stirring, and continue stirring for 5-10 minutes. While stirring, start adding component A and component B simultaneously. Component A should be added for 80-120 minutes, and component B for 90-140 minutes. Maintain the temperature at the end of the dropping process for 50-150 minutes. After the heat preservation is completed, add deionized water to dilute and stir until uniform to obtain a small molecule polymer with a molecular weight between 14,000 and 16,000. (3) Preparation of pre-coated small molecule polymers: The thickener is dissolved in deionized water, and after complete dissolution, it is added to the small molecule polymer and stirred thoroughly to obtain the final product. (4) The macromolecular polymer and the pre-coated small molecule polymer are compounded and premixed in proportion and stirred until completely mixed to obtain the final product.

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