Viscosity reduction type polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention relates to the field of water reducing agents, in particular to a viscosity reduction type polycarboxylic acid water reducing agent and a preparation method thereof. The viscosity reduction type polycarboxylic acid water reducer comprises the following raw materials: polycarboxylic acid mother liquor, a wetting agent, a defoaming agent, acrylate resin, a retarder, an air entraining agent, a viscosity reduction dispersion composition and the like. The polycarboxylate superplasticizer prepared by the invention not only has excellent viscosity-reducing and water-reducing performance, but also can keep excellent environmental adaptability and appropriate viscosity at the same time, so that the problem that the requirements of high water-reducing rate and low viscosity are difficult to meet at the same time due to increase of system viscosity is avoided, and meanwhile, the polycarboxylate superplasticizer can keep good resistance to high temperature, high humidity and the like; the probability of common problems such as viscosity rebound and too fast slump loss is greatly reduced, so that the comprehensive performance of the polycarboxylate superplasticizer and concrete is improved, the continuously increasing performance requirements of the product in the existing building material field are met, and the polycarboxylate superplasticizer has excellent application effect and popularization potential.

Description

Technical Field

[0001] The present application relates to the field of water reducers, and more specifically to a viscosity-reducing polycarboxylate water reducer and a preparation method thereof. Background Art

[0002] With the rapid development of the construction industry, the requirements for concrete performance are becoming increasingly stringent. To meet the requirements for fluidity, strength, and durability during construction, the use of high-efficiency water reducers has become particularly important. Various types of water reducers are widely used in high-performance concrete due to their excellent dispersibility and adaptability.

[0003] Among them, polycarboxylate superplasticizers, as third-generation high-performance water reducers, have become a core material in the field of modern concrete admixtures due to their advantages, including high water reduction rates, low dosages, and highly designable molecular structures. Their mechanism of action primarily relies on the electrostatic repulsion of cement particles by anionic groups (such as carboxylic acid groups) on the polycarboxylate backbone, combined with the steric hindrance of the side-chain polyether structure, effectively dispersing cement particles and improving concrete workability. However, as concrete technology evolves toward high-strength, ultra-high pumpability, and self-compacting properties, higher performance requirements are being placed on water reducers, especially for low-viscosity concrete, which is becoming increasingly urgent. Against this backdrop, research on viscosity-reducing polycarboxylate superplasticizers has become an industry hotspot.

[0004] Therefore, in recent years, the research and development of viscosity-reducing polycarboxylate superplasticizers has made outstanding progress. This type of superplasticizer not only has the advantages of traditional polycarboxylate superplasticizers, but can also effectively reduce the viscosity of concrete and improve the rheological properties of concrete. However, despite the significant progress made in viscosity-reducing polycarboxylate superplasticizers, some technical challenges still exist. For example, the compatibility of polycarboxylate superplasticizers in compound systems is poor, which can easily cause stratification, crystallization or adsorption competition, resulting in fluctuations in concrete properties. In order to achieve high dispersibility, some polycarboxylate superplasticizers usually add too many active groups and chain segments, which can easily lead to molecular chain entanglement and increase the viscosity of the system, making it difficult to simultaneously meet the requirements of high water reduction rate and low viscosity. In addition, some existing viscosity-reducing polycarboxylate superplasticizers have weak environmental adaptability. They are more sensitive to the environment, especially in high temperature, high humidity and corrosive environments, and are prone to viscosity rebound, rapid slump loss and reduced overall performance. Summary of the Invention

[0005] Therefore, in order to further solve the above-mentioned application problems, the present application provides a viscosity-reducing polycarboxylate water-reducing agent and a preparation method thereof. The polycarboxylate water-reducing agent prepared in the present application not only has excellent viscosity-reducing and water-reducing performance, but also can maintain excellent environmental adaptability and suitable viscosity at the same time, avoiding the problem of difficulty in simultaneously meeting the requirements of high water reduction rate and low viscosity due to increased system viscosity, while also maintaining good resistance to high temperature and high humidity, greatly reducing the probability of common problems such as viscosity rebound and excessive slump loss, thereby improving the comprehensive performance of the polycarboxylate water-reducing agent and concrete, meeting the growing performance requirements for such products in the existing building materials field, and having excellent application effects and promotion potential.

[0006] The viscosity-reducing polycarboxylic acid water-reducing agent comprises, by weight, 80 to 100 parts of polycarboxylic acid mother liquor, 3 to 5 parts of wetting agent, 0.6 to 1.5 parts of defoaming agent, 10 to 20 parts of acrylate resin, 2 to 4 parts of retarder, 0.3 to 0.8 parts of air entraining agent, 1 to 3 parts of pH regulator, 5 to 12 parts of viscosity-reducing dispersing composition, and 0.4 to 1 part of rust inhibitor.

[0007] As a preferred solution, the solid content of the polycarboxylic acid mother liquor is 35-50%.

[0008] As a preferred solution, the solid content of the polycarboxylic acid mother liquor is 40-45%.

[0009] As a preferred solution, the wetting agent is at least one of alkyl glycoside, isomeric alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate.

[0010] As a preferred solution, the wetting agent is alkyl glycoside and / or fatty alcohol polyoxyethylene ether.

[0011] As a preferred solution, the wetting agent is alkyl glycoside.

[0012] As a preferred solution, the defoaming agent is at least one of tributyl phosphate or silicone defoaming agent.

[0013] As a preferred solution, the defoaming agent is an organosilicon defoaming agent.

[0014] As a preferred solution, the acrylate resin is a modified acrylate resin.

[0015] As a preferred solution, the preparation method of the modified acrylic resin specifically includes the following steps: S1: mixing methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate, sodium lauryl sulfate and deionized water, and homogenizing and emulsifying at high speed; S2: heating under nitrogen protection and simultaneously adding an aqueous ammonium persulfate solution and perfluorooctyl acrylate dropwise, and after the addition is completed, keeping the temperature for reaction while maintaining high-speed stirring; S3: after the reaction is completed, cooling and adding sodium hydroxide to adjust the pH, filtering and controlling the solid content to obtain the product.

[0016] As a preferred solution, the preparation method of the modified acrylic resin specifically includes the following steps: S1: methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate, sodium lauryl sulfate and deionized water are mixed, and emulsified in a high-speed homogenizer at a speed of 1500-2000 rpm for 30-40 minutes to form a stable pre-emulsion; S2: the pre-emulsion is transferred to a reactor, heated to 75-80°C under nitrogen protection, and then an aqueous ammonium persulfate solution and perfluorooctyl acrylate are simultaneously added dropwise, with the dropping time controlled to be 1-1.5 hours. After the dropwise addition is completed, the reaction is kept warm for 5-6 hours, during which the stirring speed is maintained at 400-500 rpm; S3: after the reaction is completed, the temperature is lowered to 35-40°C, sodium hydroxide is added to adjust the pH to 7-7.5, and the mixture is filtered through a 200-300 mesh sieve to control the solid content to 45-55%.

[0017] As a preferred solution, the mass ratio of methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate and perfluorooctyl acrylate is (5-6.5):(1.3-1.6):(1.3-1.6):(0.9-1.2).

[0018] As a preferred solution, the mass ratio of methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate and perfluorooctyl acrylate is (5.5-6): (1.4-1.5): (1.4-1.5): (0.9-1).

[0019] The addition of the acrylic resin in this application can effectively improve the viscosity-reducing properties of the polycarboxylate water-reducing agent while maintaining its excellent heat resistance and water resistance, significantly reducing the probability of common problems such as viscosity rebound and rapid slump loss, thereby improving the overall performance of the polycarboxylate water-reducing agent and concrete. The methyl methacrylate in the acrylic resin provides a rigid skeleton, enhancing the anchoring ability of the molecular chain on the surface of cement particles. The sulfonic acid groups contained in the acrylic resin maintain dispersion stability at high temperatures through electrostatic repulsion, creating a higher heat resistance effect than the carboxylic acid groups. The existing fluorine segments form a low-surface-energy hydrophobic layer, reducing water intrusion into the capillaries and significantly reducing the intrusion efficiency of water molecules and corrosive media through chelation.

[0020] On the other hand, the sulfonic acid groups and the carboxylic acid groups of the polycarboxylic acid main chain form a double electric layer, expanding the range of electrostatic repulsion, and further forming a molecular brush effect on the surface of cement particles through fluorine chain side branches, inhibiting the approach of particles through steric hindrance, greatly increasing steric hindrance, and cooperating with the adsorption of phosphate groups on the surface of cement particles to form a lubricating layer with a low friction coefficient, thereby achieving an overall viscosity reduction effect on concrete.

[0021] As a preferred solution, the mass ratio of the polycarboxylic acid mother solution, the acrylic ester resin and the viscosity-reducing dispersion composition is (90-100): (14-20): (8-12).

[0022] As a preferred solution, the mass ratio of the polycarboxylic acid mother solution, the acrylic ester resin and the viscosity-reducing dispersion composition is (95-100): (16-20): (10-11).

[0023] As a preferred solution, the retarder is at least one of sodium gluconate, trisodium citrate, sodium polyaspartate, tartaric acid and calcium lignin sulfonate.

[0024] As a preferred solution, the retarder is sodium gluconate or trisodium citrate.

[0025] As a preferred solution, the retarder is trisodium citrate.

[0026] As a preferred solution, the air entraining agent is at least one of rosin, sodium lauryl sulfate, triterpenoid saponin and alkylphenol polyoxyethylene ether.

[0027] As a preferred solution, the air entraining agent is rosin or triterpenoid saponin.

[0028] As a preferred solution, the air entraining agent is triterpenoid saponin.

[0029] As a preferred solution, the pH regulator is at least one of sodium hydroxide, triethanolamine, sodium bicarbonate and potassium dihydrogen phosphate.

[0030] As a preferred solution, the pH regulator is triethanolamine.

[0031] As a preferred solution, the viscosity-reducing and dispersing composition is a composition of polyvinyl pyrrolidone, sodium polyaspartate and magnesium lignin sulfonate.

[0032] As a preferred solution, the mass ratio of polyvinyl pyrrolidone, sodium polyaspartate and magnesium lignin sulfonate is (4-5): (2-3): (2-3).

[0033] As a preferred solution, the mass ratio of polyvinyl pyrrolidone, sodium polyaspartate and magnesium lignin sulfonate is 4.5:3:2.5.

[0034] The addition of viscosity reducing and dispersing composition improves the performance of polycarboxylate water reducer comprehensively. Long chain polyvinyl pyrrolidone is adsorbed on the surface of cement particles through hydrogen bonds, forming an adsorption layer of a certain thickness, which helps to prevent the particles from approaching. It is partially hydrolyzed at high temperature and releases the retarding effect. The α-carboxylic acid group of sodium polyaspartate and Ca 2 + Forming a stable complex, inhibiting hydration to form CSH gel, prolonging the induction period, and adsorbing between cement particles through linear molecular structure, reducing particle friction through electrostatic repulsion and molecular chain slip, and finally adsorbing on the surface of cement particles through sulfonic acid groups and phenolic hydroxyl groups in the system, maintaining dispersion stability through the dual effects of electrostatic repulsion and steric hindrance, and then filling the capillaries with lignin molecules, reducing porosity and reducing viscosity rebound caused by water migration, ensuring the comprehensive performance of the polycarboxylate water reducer.

[0035] As a preferred solution, the rust inhibitor is a combination of sodium molybdate and tannic acid.

[0036] As a preferred solution, the mass ratio of sodium molybdate to tannic acid is (8-11):(2-4).

[0037] As a preferred solution, the mass ratio of sodium molybdate to tannic acid is (9-10):(2.5-3).

[0038] The preparation method of the above-mentioned viscosity-reducing polycarboxylate water-reducing agent specifically comprises the following steps: S1: adding a polycarboxylate mother liquor and an acrylate resin to a reactor, controlling the temperature to 40-45°C, stirring at a speed of 200-300 rpm for 20-30 minutes, and mixing uniformly; S2: sequentially adding a viscosity-reducing dispersion composition, a wetting agent, and a retarder, raising the temperature to 50-55°C, and ultrasonically dispersing at 500-600W and 40kHz for 15-20 minutes, then sequentially adding the remaining raw materials except the pH adjuster, stirring at a speed of 200-240 rpm for 10-15 minutes each time; S3: after the above is completed, adding a pH adjuster to adjust the pH to 6.5-7.5, stirring at a speed of 100-150 rpm for 10-15 minutes, and passing the product through a 200-300 mesh sieve to control the solid content within the range of 35-40%.

[0039] This application has the following beneficial effects:

[0040] 1. The viscosity-reducing polycarboxylate water-reducing agent finally prepared in this application not only has excellent viscosity-reducing and water-reducing performance, but also can maintain excellent environmental adaptability and suitable viscosity. It avoids the problem of difficulty in simultaneously meeting the requirements of high water reduction rate and low viscosity due to increased system viscosity. At the same time, it can also maintain good resistance to high temperature and high humidity, greatly reducing the probability of common problems such as viscosity rebound and rapid slump loss, thereby improving the comprehensive performance of polycarboxylate water-reducing agent and concrete, meeting the growing performance requirements for such products in the existing building materials field, and has excellent application effects and promotion potential.

[0041] 2. The viscosity-reducing polycarboxylate water-reducing agent finally prepared in this application can effectively improve the viscosity-reducing performance of the polycarboxylate water-reducing agent by adding a specific acrylate resin, while maintaining its good heat resistance, water resistance and other properties; the methyl methacrylate in the acrylate resin provides a rigid skeleton, enhancing the anchoring ability of the molecular chain on the surface of cement particles, and the sulfonic acid group contained therein maintains dispersion stability at high temperatures through electrostatic repulsion, creating a higher heat resistance effect than the carboxylic acid group. The existing fluorine chain segment reduces the intrusion of water into the capillaries while forming a low surface energy hydrophobic layer, and greatly reduces the intrusion efficiency of water molecules and corrosive media through chelation.

[0042] 3. The viscosity-reducing polycarboxylate water-reducing agent finally prepared by the present application, wherein the viscosity-reducing dispersing composition added thereto is adsorbed on the surface of cement particles through hydrogen bonds, forming an adsorption layer of a certain thickness, helping to prevent the particles from approaching, and partially hydrolyzing at high temperatures to release the retarding effect; the α-carboxylic acid group of sodium polyaspartate and Ca 2+ Forming a stable complex, inhibiting hydration to form CSH gel, prolonging the induction period, and adsorbing between cement particles through linear molecular structure, reducing particle friction through electrostatic repulsion and molecular chain slippage, and finally adsorbing on the surface of cement particles through sulfonic acid groups and phenolic hydroxyl groups in the system, maintaining dispersion stability through the dual effects of electrostatic repulsion and steric hindrance, and then filling the capillaries with lignin molecules, reducing porosity and reducing viscosity rebound caused by water migration. DETAILED DESCRIPTION

[0043] Example 1

[0044] The viscosity-reducing polycarboxylic acid water-reducing agent comprises, by weight, 98.5 parts of polycarboxylic acid mother liquor, 3.6 parts of wetting agent, 0.8 part of defoaming agent, 17.5 parts of acrylate resin, 3.1 parts of retarder, 0.6 part of air entraining agent, 1.6 parts of pH regulator, 10.2 parts of viscosity-reducing dispersing composition, and 0.8 part of rust inhibitor.

[0045] The solid content of the polycarboxylic acid mother liquor was 40%, and the polycarboxylic acid mother liquor product of model WR900 was purchased from Hunan Zhongyan Building Materials Technology Co., Ltd. in China.

[0046] The wetting agent is alkyl glycoside; the defoaming agent is silicone defoaming agent BYK-066N; the retarder is trisodium citrate; the air entraining agent is triterpenoid saponin; the pH regulator is triethanolamine; and the rust inhibitor is a combination of sodium molybdate and tannic acid, with a mass ratio of 9.5:2.5.

[0047] The viscosity-reducing and dispersing composition is a composition of polyvinyl pyrrolidone K60, sodium polyaspartate and magnesium lignin sulfonate, with a mass ratio of 4.5:3:2.5.

[0048] Sodium polyaspartate was purchased from industrial-grade sodium polyaspartate products sold by Hebei Huashun Chemical Co., Ltd., China.

[0049] The preparation method of the modified acrylic resin specifically comprises the following steps, calculated by mass: S1: mixing 6 parts of methyl methacrylate, 1.5 parts of sodium p-styrene sulfonate, 1.5 parts of 2-hydroxyethyl methacrylate phosphate, 0.05 parts of sodium lauryl sulfate and 30 parts of deionized water, and emulsifying the mixture in a high-speed homogenizer at a speed of 1800 rpm for 35 minutes to form a stable pre-emulsion; S2: transferring the pre-emulsion to a reactor, heating the mixture to 80°C under nitrogen protection, and then simultaneously adding dropwise a solution containing 0.06 parts of an ammonium persulfate aqueous solution (2 parts in total) and 0.9 parts of perfluorooctyl acrylate, with the dropping time controlled to 1 hour. After the dropwise addition is completed, the mixture is kept warm for reaction for 5 hours, during which the stirring speed is maintained at 500 rpm; S3: after the reaction is completed, the mixture is cooled to 40°C, sodium hydroxide is added to adjust the pH to 7.5, and the mixture is filtered through a 200-mesh sieve to control the solid content to 48%, thereby obtaining the product.

[0050] The preparation method of a viscosity-reducing polycarboxylate water-reducing agent specifically comprises the following steps: S1: adding a polycarboxylate mother liquor and an acrylate resin to a reactor, controlling the temperature to 40° C., stirring at 300 rpm for 25 minutes, and mixing uniformly; S2: sequentially adding a viscosity-reducing dispersion composition, a wetting agent, and a retarder, raising the temperature to 50° C., and ultrasonically dispersing at 500W and 40kHz for 15 minutes, then sequentially adding the remaining raw materials except a pH regulator, stirring at 200 rpm for 10 minutes each time; S3: after the above steps are completed, adding a pH regulator to adjust the pH to 7.5, stirring at 120 rpm for 15 minutes, and passing the product through a 250-mesh sieve to control the solid content to 40%.

[0051] Example 2

[0052] This embodiment differs from Embodiment 1 only in the following: the raw materials of the viscosity-reducing polycarboxylic acid water-reducing agent, in parts by mass, include: 90 parts of polycarboxylic acid mother liquor, 3.2 parts of wetting agent, 0.7 part of defoaming agent, 14.5 parts of acrylic resin, 2.6 parts of retarder, 0.5 part of air entraining agent, 1.8 parts of pH regulator, 8.6 parts of viscosity-reducing dispersing composition, and 0.8 part of rust inhibitor.

[0053] The viscosity-reducing and dispersing composition is a composition of polyvinyl pyrrolidone K60, sodium polyaspartate and magnesium lignin sulfonate, with a mass ratio of 5:2:2.

[0054] Example 3

[0055] The only difference between this embodiment and Example 1 is that the raw materials of the viscosity-reducing polycarboxylic acid water-reducing agent, calculated by mass, include: 100 parts of polycarboxylic acid mother liquor, 3.8 parts of wetting agent, 0.9 part of defoaming agent, 20 parts of acrylic resin, 3.3 parts of retarder, 0.6 part of air entraining agent, 2.1 parts of pH regulator, 8 parts of viscosity-reducing dispersing composition, and 0.8 part of rust inhibitor.

[0056] The viscosity-reducing and dispersing composition is a composition of polyvinyl pyrrolidone K60, sodium polyaspartate and magnesium lignin sulfonate, with a mass ratio of 4:3:3.

[0057] Comparative Example 1

[0058] The only difference between this comparative example and Example 1 is that the raw materials of the viscosity-reducing polycarboxylic acid water-reducing agent, calculated by mass, include: 115.5 parts of polycarboxylic acid mother liquor, 3.6 parts of wetting agent, 0.8 part of defoaming agent, 7.5 parts of acrylic resin, 3.1 parts of retarder, 0.6 part of air entraining agent, 1.6 parts of pH regulator, 12.5 parts of viscosity-reducing dispersion composition, and 0.8 part of rust inhibitor.

[0059] Comparative Example 2

[0060] The only difference between this comparative example and Example 1 is that the raw materials of the viscosity-reducing polycarboxylic acid water-reducing agent, calculated by mass, include: 105 parts of polycarboxylic acid mother liquor, 3.6 parts of wetting agent, 0.8 part of defoaming agent, 20.5 parts of acrylate resin, 3.1 parts of retarder, 0.6 part of air entraining agent, 1.6 parts of pH regulator, 3.5 parts of viscosity-reducing dispersion composition, and 0.8 part of rust inhibitor.

[0061] Comparative Example 3

[0062] This comparative example differs from Example 1 only in the following: the preparation method of the modified acrylic resin, in parts by mass, specifically comprises the following steps: S1: 10 parts of methyl methacrylate, 0.5 parts of sodium p-styrenesulfonate, 0.5 parts of 2-hydroxyethyl methacrylate phosphate and 0.05 parts of sodium lauryl sulfate are mixed with 30 parts of deionized water, and emulsified in a high-speed homogenizer at a speed of 1800 rpm for 35 minutes to form a stable pre-emulsion; S2: the pre-emulsion is transferred to a reactor, heated to 80° C. under nitrogen protection, and then a solution containing 0.06 parts of ammonium persulfate aqueous solution (2 parts in total) and 1.8 parts of perfluorooctyl acrylate are simultaneously added dropwise, the dropping time being controlled to 1 hour, and after the dropwise addition is completed, the reaction is kept warm for 5 hours, during which the stirring speed is maintained at 500 rpm; S3: after the reaction is completed, the temperature is lowered to 40° C., sodium hydroxide is added to adjust the pH to 7.5, and the mixture is filtered through a 200-mesh sieve to control the solid content to 48%, thereby obtaining the product.

[0063] Comparative Example 4

[0064] This comparative example differs from Example 1 only in the following: the preparation method of the modified acrylic resin, in parts by mass, specifically comprises the following steps: S1: 4.5 parts of methyl methacrylate, 2 parts of sodium p-styrene sulfonate, 2.5 parts of 2-hydroxyethyl methacrylate phosphate, 0.05 parts of sodium lauryl sulfate and 30 parts of deionized water are mixed, and emulsified in a high-speed homogenizer at a speed of 1800 rpm for 35 minutes to form a stable pre-emulsion; S2: the pre-emulsion is transferred to a reactor, heated to 80° C. under nitrogen protection, and then a solution containing 0.06 parts of ammonium persulfate aqueous solution (2 parts in total) and 0.2 parts of perfluorooctyl acrylate are simultaneously added dropwise, the dropping time being controlled to 1 hour, and after the dropwise addition is completed, the reaction is kept warm for 5 hours, during which the stirring speed is maintained at 500 rpm; S3: after the reaction is completed, the temperature is lowered to 40° C., sodium hydroxide is added to adjust the pH to 7.5, and the mixture is filtered through a 200-mesh sieve to control the solid content to 48%, thereby obtaining the product.

[0065] Comparative Example 5

[0066] The only difference between this comparative example and Example 1 is that the viscosity-reducing and dispersing composition is a composition of polyvinylpyrrolidone K60, sodium polyaspartate and magnesium lignin sulfonate, with a mass ratio of 9:0.5:1.

[0067] Comparative Example 6

[0068] The only difference between this comparative example and Example 1 is that the viscosity-reducing and dispersing composition is a composition of polyvinylpyrrolidone K60, sodium polyaspartate and magnesium lignin sulfonate, with a mass ratio of 2:5:4.

[0069] Performance Testing

[0070] 1. Water reduction rate test: The water reduction rate test was carried out on the water reducing agents prepared in the examples and comparative examples. The reference concrete preparation was: cement (CEM I 42.5) 450 kg / m 3 , water-cement ratio 0.50, sand rate 40%, slump 190±10mm; add water reducer according to 0.8% of the mass of cementitious material, adjust the water consumption to the benchmark slump, calculate the water reduction rate by the benchmark water consumption and the water consumption after using water reducer, water reduction rate % = (baseline water consumption - water consumption after using water reducer) / benchmark water consumption × 100%, take the average value of 10 tests and record it in Table 1.

[0071] 2. Viscosity reduction test: According to the conditions and water reducer dosage in performance test 1, a rotational viscometer was used for the test, with rotor No. 3 and a speed of 50 rpm. Sample preparation: fresh concrete was sieved through a 5 mm sieve to obtain the slurry. The test temperature was 20±2°C. The viscosity value at a shear rate of 10 to 100 s-1 was recorded, and the data at 50 s-1 was taken. The viscosity of the benchmark concrete slurry was 1050 to 1100 mPa·s. The results were recorded as the average of 10 tests in Table 1.

[0072] 3. Slump loss test over time: According to the conditions and water-reducing agent dosage in performance test 1, the slump of freshly mixed benchmark concrete is 190±10mm. The test standing conditions are 40℃ and 80% relative humidity. After standing for 2 hours, retest. The results are the average of 10 tests and recorded in Table 1.

[0073] 4. Temperature stability test: Place the water reducer solution in a 60℃ oven, take it out every 24 hours and cool it to 25℃, observe the viscosity change, and continue for 7 days. Take the viscosity retention rate after the test, and take the average of 10 tests and record it in Table 1.

[0074] Table 1 Performance test results of embodiments and comparative examples

[0075]

[0076] Judging from the final performance test results of the embodiments and comparative examples, comparative examples 1 to 6 achieved worse performance results than the embodiments, while the embodiments used the better technical solution defined in the present application, adopting an acrylic resin with better performance and a functional composition to work together to prevent cement particles from approaching and connecting with each other, and partially hydrolyze at high temperature to release the retarding effect. On the other hand, they are adsorbed between cement particles through a linear molecular structure, reducing particle friction through electrostatic repulsion and molecular chain slippage, and finally adsorbed on the surface of cement particles through sulfonic acid groups and phenolic hydroxyl groups in the system, maintaining dispersion stability through the dual effects of electrostatic repulsion and steric hindrance, thereby filling capillaries, reducing porosity, reducing moisture penetration and viscosity rebound caused by migration, and ensuring overall high-level comprehensive performance.

Claims

1. A viscosity-reducing polycarboxylate water-reducing agent, characterized in that: The raw materials include, by weight: 80 to 100 parts of polycarboxylic acid mother liquor, 3 to 5 parts of wetting agent, 0.6 to 1.5 parts of defoaming agent, and 10 to 20 parts of acrylate resin; The preparation method of the modified acrylic resin comprises: S1: mixing methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate, sodium lauryl sulfate and deionized water, and high-speed homogenization and emulsification; S2: heating and dropwise adding an aqueous ammonium persulfate solution and perfluorooctyl acrylate, and keeping the temperature; S3: after the reaction is completed, cooling and adjusting the pH, and filtering to obtain the modified acrylic resin; The mass ratio of the methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate and perfluorooctyl acrylate is (5-6.5): (1.3-1.6): (1.3-1.6): (0.9-1.2).

2. The viscosity-reducing polycarboxylate water-reducing agent according to claim 1, characterized in that: In parts by mass, the raw materials are The invention comprises the following components: 2 to 4 parts of retarder, 0.3 to 0.8 parts of air entraining agent, 5 to 12 parts of viscosity reducing dispersion composition, 0.4 to 1 part of rust inhibitor and 1 to 3 parts of pH regulator.

3. The viscosity-reducing polycarboxylate water-reducing agent according to claim 2, characterized in that: The mass ratio of the polycarboxylic acid mother solution, the acrylic ester resin and the viscosity-reducing dispersion composition is (90-100): (14-20): (8-12).

4. The viscosity-reducing polycarboxylate water-reducing agent according to claim 3, characterized in that: The preparation method of the modified acrylic resin specifically comprises the following steps: S1: mixing methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate, sodium lauryl sulfate and deionized water, and emulsifying the mixture in a high-speed homogenizer at a rotation speed of 1500-2000 rpm for 30-40 minutes to form a stable pre-emulsion; S2: transferring the pre-emulsion to a reactor, heating the mixture to 75-80°C under nitrogen protection, then simultaneously adding an aqueous ammonium persulfate solution and perfluorooctyl acrylate dropwise, controlling the dropping time to be 1-1.5 hours, and maintaining the temperature for reaction for 5-6 hours after the dropwise addition is completed, during which the stirring speed is maintained at 400-500 rpm; S3: after the reaction is completed, cooling the mixture to 35-40°C, adding sodium hydroxide to adjust the pH to 7-7.5, filtering the mixture through a 200-300 mesh sieve, and controlling the solid content to be 45-55%, thereby obtaining the modified acrylic resin.

5. The viscosity-reducing polycarboxylate water-reducing agent according to claim 4, characterized in that: The mass ratio of the methyl methacrylate, sodium p-styrene sulfonate, 2-hydroxyethyl methacrylate phosphate and perfluorooctyl acrylate is (5.5-6): (1.4-1.5): (1.4-1.5): (0.9-1).

6. The viscosity-reducing polycarboxylate water-reducing agent according to claim 5, characterized in that: The solid content of the polycarboxylic acid mother liquor is 35-50%; the wetting agent is at least one of alkyl glycoside, isomeric alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate.

7. The viscosity-reducing polycarboxylate water-reducing agent according to claim 6, characterized in that: The viscosity reducing and dispersing composition is a composition of polyvinyl pyrrolidone, sodium polyaspartate and magnesium lignin sulfonate.

8. The viscosity-reducing polycarboxylate water-reducing agent according to claim 7, characterized in that: The mass ratio of the polyvinyl pyrrolidone, sodium polyaspartate and magnesium lignin sulfonate is (4-5): (2-3): (2-3).

9. The viscosity-reducing polycarboxylate water-reducing agent according to claim 8, characterized in that: The rust preventive is a composition of sodium molybdate and tannic acid, with a mass ratio of (8-11): (2-4).

10. A method for preparing the viscosity-reducing polycarboxylate water-reducing agent according to any one of claims 1 to 9, characterized in that: The specific steps include: S1: Add the polycarboxylic acid mother liquor and acrylic resin into the reactor, control the temperature to 40-45°C, stir at 200-300 rpm for 20-30 minutes, and mix evenly; S2: adding the viscosity reducing dispersion composition, the wetting agent and the retarder in sequence, raising the temperature to 50-55° C., and ultrasonically dispersing at 500-600 W and 40 kHz for 15-20 minutes, then adding the remaining raw materials except the pH adjuster in sequence, stirring at 200-240 rpm for 10-15 minutes each time; S3: after the above is completed, adding the pH adjuster to adjust the pH to 6.5-7.5, stirring at 100-150 rpm for 10-15 minutes, and passing the product through a 200-300 mesh sieve to control the solid content within the range of 35-40%.

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