Process for preparing nano-silica modified polycarboxylate superplasticizer by tip ultrasonic

Abstract

The application discloses a process for preparing nano-silica modified polycarboxylic acid water reducing agent by using a tip ultrasonic device, which comprises the following steps: S1, preparing a maleic acid solution and a hydrogen peroxide solution by respectively dissolving maleic acid and hydrogen peroxide in distilled water, and preparing a mixed solution of mercaptopropionic acid and ascorbic acid by dissolving mercaptopropionic acid and ascorbic acid in distilled water; S2, mixing and dissolving equal-molar-ratio methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether in distilled water to prepare a mixed solution, then adding the hydrogen peroxide solution, and sequentially adding the maleic acid solution, the mixed solution of mercaptopropionic acid and ascorbic acid and a nano-SiO2 suspension solution drop by drop, respectively completing the dropwise addition within 1.5-2 h, 2-3 h and 1.5-2 h, and performing tip ultrasonic treatment; and S3, after heat preservation for 1-2 h, cooling to room temperature. The application improves the stability and long-acting property of dispersion in cement-based materials such as concrete, and realizes long-time enhancement effect on macroscopic properties of the cement-based materials, including mechanical properties and working properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a process for preparing nano-silica modified polycarboxylate superplasticizer by tip ultrasonic. BACKGROUND

[0002] Water reducing agent is an additive that can reduce the water consumption during the preparation of cement-based materials such as concrete and cement without changing the workability of the concrete, and polycarboxylate superplasticizer is widely used in highway, bridge, dam, tunnel, high-rise building and other engineering projects. However, polycarboxylate superplasticizer also has some problems, such as low strength and low water-reducing rate.

[0003] Therefore, more and more researches have been conducted on polycarboxylate superplasticizer. For example, a concrete water reducing agent and its preparation method are disclosed in Chinese patent CN 108424025A, which comprises the following raw materials by weight: iso-pentenyl alcohol polyoxyethylene ether 35-45 parts, maleic anhydride 70-80 parts, methyl acrylate 5-10 parts, polypropylene glycol bisacrylate 15-20 parts, sodium methallyl sulfonate 3-8 parts, initiator 0.8-1.3 parts, chain transfer agent 1-1.5 parts, sodium hydroxide 50-60 parts and water 200-300 parts. Although this prior art can improve the water-reducing rate to some extent, the dispersion uniformity and fineness of the polycarboxylate superplasticizer in cement-based materials such as concrete are generally poor, and the improvement of water content and the improvement of macroscopic properties including mechanical properties and working properties are not ideal.

[0004] To solve the above problems, the article "Preparation and Performance Research of Nano-Silica Modified Polycarboxylate Superplasticizer" in the Journal of Southwest University of Science and Technology, Vol. 35, No. 2, discloses a technical solution for preparing a nano-silica modified polycarboxylate superplasticizer by mixing a certain amount of acrylic acid and distilled water to obtain solution A, mixing a certain amount of mercaptopropionic acid, ascorbic acid and distilled water to obtain solution B, gradually heating a certain amount of isopentenyl alcohol polyoxyethylene ether and a proper amount of distilled water, stirring until the isopentenyl alcohol polyoxyethylene ether is dissolved, and then adding a certain amount of hydrogen peroxide solution to obtain solution C, and then slowly adding solutions A, B and a nano-silica solution into solution C through a peristaltic pump, with the dropping time controlled at 2 h, 2.5 h and 2 h respectively, and then continuing to heat the system for 1.5 h and then cooling to room temperature. This prior art improves the dispersion uniformity and fineness in cement-based materials such as concrete, improves the microstructure density of the hardened cement-based body, and improves the strength, but the dispersion stability and long-term effect of the nano-silica modified polycarboxylate superplasticizer in cement-based materials such as concrete are still insufficient, the overall dispersion effect and dispersion retention capacity are still general, and the long-term enhancement effect on the macroscopic properties of the cement-based material including the mechanical properties and working properties cannot be ensured, and the reduction of the mixing amount is still limited, and the adaptability to different cement-based materials is also general.

[0005] Therefore, a new technical solution is needed to solve the above technical problems. SUMMARY

[0006] The present application aims to provide a process for preparing a nano-silica modified polycarboxylate superplasticizer by tip ultrasonic, to solve the technical problems of the prior art nano-silica modified polycarboxylate superplasticizer disclosed in the background art, which has insufficient dispersion stability and long-term effect in cement-based materials such as concrete, the overall dispersion effect and dispersion retention capacity are still general, and the long-term enhancement effect on the macroscopic properties of the cement-based material including the mechanical properties and working properties cannot be ensured, and the reduction of the mixing amount is limited, and the adaptability to different cement-based materials is also general.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solution:

[0008] A process for preparing a nano-silica modified polycarboxylate superplasticizer by tip ultrasonic, comprising the following steps:

[0009] S1, preparing respective solutions of maleic acid and hydrogen peroxide with distilled water, and preparing a mixed solution of mercaptopropionic acid and ascorbic acid with distilled water, the content of mercaptopropionic acid and ascorbic acid in the mixed solution of mercaptopropionic acid and ascorbic acid being 0.5-1% and 1-2% respectively;

[0010] S2, the equimolar ratio of methyl allyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is mixed and dissolved in distilled water, after preparing the mixed solution, hydrogen peroxide solution is added first, then the mixed solution of maleic acid, mercaptopropionic acid and ascorbic acid and nano-silica suspension are added in turn, the adding of the mixed solution of maleic acid, mercaptopropionic acid and ascorbic acid and nano-silica suspension is completed in 1.5-2 h, 2-3 h and 1.5-2 h respectively, and the tip ultrasonic is carried out, wherein the temperature of the tip ultrasonic is 20-70 DEG C, the power is 50-600 W, and the time is 10-120 min;

[0011] S3, after heat preservation for 1-2 h, cooling to room temperature, the nano-silica modified polycarboxylate superplasticizer is prepared;

[0012] Further, the mass percentage of the effective component hydrogen peroxide in the hydrogen peroxide relative to the mixed methyl allyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 0.1-0.3%, the mass percentage of the mercaptopropionic acid relative to the mixed methyl allyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 0.3-0.5%, the mass percentage of the nano-silica relative to the mixed methyl allyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 5-30%, and the acid-ether ratio of the maleic acid to the mixed methyl allyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 2.8-4.4:1.

[0013] Compared with the prior art, the beneficial effects of the present application are:

[0014] 1. The methyl allyl alcohol polyoxyethylene ether, iso-pentenyl alcohol polyoxyethylene ether, maleic acid, hydrogen peroxide, ascorbic acid and mercaptopropionic acid in the present application are creatively matched with nano-silica in the environment of tip ultrasonic, which further synergistically enhances the working mechanism of electrostatic repulsion and steric hindrance for the preparation of nano-silica modified polycarboxylate superplasticizer, can effectively adapt to different cement-based materials, and can long-term stably fully play the pozzolanic reaction, nucleation effect and filling effect in the cement-based materials, long-term regulates the structure of the cement-based materials from the microscale, greatly improves the dispersion stability and long-acting property in the cement-based materials such as concrete while reducing the dosage, thereby greatly improves the overall dispersion effect and dispersion retention capacity, and ensures the long-time enhancement effect on the macroscopic properties of the cement-based materials including mechanical properties and working properties;

[0015] 2. The graft reaction of nanosilica with equal molar ratio of isopentenyl alcohol polyoxyethylene ether and methyl propenyl alcohol polyoxyethylene ether in the preparation process of the polycarboxylic acid water reducing agent in the application, and the addition amount and addition time of methyl propenyl alcohol polyoxyethylene ether, isopentenyl alcohol polyoxyethylene ether, maleic acid, hydrogen peroxide, ascorbic acid, mercaptopropionic acid and nanosilica, and the mass concentration of the solution prepared respectively, effectively avoid the problem of cement-based material retardation, further greatly reduce the dosage, effectively ensure the enhancement effect on the macroscopic performance including mechanical properties and working performance, and further improve the use adaptability for cement-based materials. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The infrared spectrum of the nanosilica modified polycarboxylic acid water reducing agent in Example 1 of the application. DETAILED DESCRIPTION

[0017] In order to deepen the understanding of the application, the application will be further described in detail below in combination with examples. Example 1:

[0018] Preparation of the nanosilica modified polycarboxylic acid water reducing agent:

[0019] S1, raw materials: methyl propenyl alcohol polyoxyethylene ether (HPEG), isopentenyl alcohol polyoxyethylene ether (TPEG), maleic acid (MA), hydrogen peroxide (w(H2O2) = 27.5%), ascorbic acid (VC), mercaptopropionic acid (MPA), nanosilica (NS), distilled water;

[0020] S2, the maleic acid with an acid-ether ratio of 4.4:1 of the mixed methyl propenyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether is prepared into a maleic acid solution with a mass concentration of 2% by using distilled water; the hydrogen peroxide (w(H2O2) = 27.5%) is prepared into a hydrogen peroxide solution with a mass concentration of 2.5% by using distilled water, wherein the amount of the effective component hydrogen peroxide in the hydrogen peroxide is 0.1% of the mass of the mixed methyl propenyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether; the mercaptopropionic acid with a mass of 0.3% of the mixed methyl propenyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether is added with ascorbic acid, and a mixed solution of mercaptopropionic acid and ascorbic acid is prepared by using distilled water, the content of the mercaptopropionic acid in the mixed solution is 0.5%, and the content of the ascorbic acid is 1%;

[0021] S3, equal molar ratio of methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether are added to distilled water, heated and stirred evenly until they are dissolved to form a mixed solution of methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether, then hydrogen peroxide solution is added to the mixed solution of methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether, and then the mixed solution of maleic acid, mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are slowly added in sequence, wherein the mixed solution of maleic acid, mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are added dropwise for 1.5-2 h, 2-3 h and 1.5-2 h respectively, and the amount of nano-silica is 5% of the mass of the mixed methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether;

[0022] S4, at 40℃, with a power of 300W, tip ultrasonic for 60min, after incubation for 1-2h, cool to room temperature, to obtain the nano-silica modified polycarboxylic acid water reducer; wherein the tip ultrasonic is operated by a tip ultrasonic instrument (model: SCIENTZ-IID), which consists of an ultrasonic generator and an ultrasonic transducer, the ultrasonic generator (power) converts 220VAC, 50Hz single-phase electricity into 20-25kHz, about 600V alternating electric energy through frequency conversion devices, and matches the impedance and power to drive the ultrasonic transducer to make longitudinal mechanical vibration, and the vibration wave produces cavitation effect on the nano-silica water reducer through the titanium alloy amplitude changer (usually called tip) immersed in the solution. The tip ultrasonic instrument is developed by combining microcomputer control, frequency selection, temperature measurement, protection and other software and hardware technologies, which has the characteristics of simple operation, accurate temperature control, stable power, etc., only need to insert the titanium alloy amplitude changer into the solution, set the specific ultrasonic temperature, power and time. Example 2:

[0023] Preparation of nano-silica modified polycarboxylic acid water reducer:

[0024] S1, raw materials: methyl allyl alcohol polyoxyethylene ether (HPEG), isopentenyl alcohol polyoxyethylene ether (TPEG), maleic acid (MA), hydrogen peroxide (w(H2O2) = 27.5%), ascorbic acid (VC), mercaptopropionic acid (MPA), nano-silica (NS), distilled water;

[0025] S2, the acid ether ratio of 2.8:1 of maleic acid with mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is prepared into a maleic acid solution with a mass concentration of 5% with distilled water; hydrogen peroxide (w(H2O2) = 27.5%) is prepared into a hydrogen peroxide solution with a mass concentration of 3% with distilled water, wherein the amount of effective component hydrogen peroxide in the hydrogen peroxide is 0.3% of the mass of mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether; 0.5% of the mass of mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether of mercaptopropionic acid is added, ascorbic acid is added, and a mixed solution of mercaptopropionic acid and ascorbic acid is prepared with distilled water, the content of mercaptopropionic acid in the mixed solution is 1%, and the content of ascorbic acid is 2%;

[0026] S3, equimolar ratio of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is added to distilled water, heated and stirred uniformly until dissolved, to form a mixed solution of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether, then hydrogen peroxide solution is added to the mixed solution of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether, and then the mixed solution of maleic acid, the mixed solution of mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are slowly added in sequence, wherein the mixed solution of maleic acid, the mixed solution of mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are added dropwise for 1.5-2 h, 2-3 h and 1.5-2 h respectively, and the amount of nano-silica is 30% of the mass of mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether;

[0027] S4, at 20°C, with a power of 50W, the tip is ultrasonicated for 120min, and after incubation for 1-2h, it is cooled to room temperature, to obtain nano-silica modified polycarboxylic acid water reducer. Example 3:

[0028] Preparation of nano-silica modified polycarboxylic acid water reducer:

[0029] S1, raw materials: methyl alkenyl alcohol polyoxyethylene ether (HPEG), iso-pentenyl alcohol polyoxyethylene ether (TPEG), maleic acid (MA), hydrogen peroxide (w(H2O2) = 27.5%), ascorbic acid (VC), mercaptopropionic acid (MPA), nano-silica (NS), distilled water;

[0030] S2, the acid ether ratio of 3.6:1 of maleic acid with mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is prepared into a maleic acid solution with a mass concentration of 3.5% with distilled water; hydrogen peroxide (w(H2O2) = 27.5%) is prepared into a hydrogen peroxide solution with a mass concentration of 2.7% with distilled water, wherein the amount of effective component hydrogen peroxide in the hydrogen peroxide is 0.2% of the mass of mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether; 0.4% of the mass of mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether of mercaptopropionic acid is added, ascorbic acid is added, and a mixed solution of mercaptopropionic acid and ascorbic acid is prepared with distilled water, the content of mercaptopropionic acid in the mixed solution is 0.7%, and the content of ascorbic acid is 1.4%;

[0031] S3, equimolar ratio of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is added to distilled water, heated and stirred uniformly until dissolved, to form a mixed solution of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether, then hydrogen peroxide solution is added to the mixed solution of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether, and then the mixed solution of maleic acid, the mixed solution of mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are slowly added in sequence, wherein the maleic acid solution, the mixed solution of mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are added dropwise for 1.5-2 h, 2-3 h and 1.5-2 h respectively, and the amount of nano-silica is 20% of the mass of mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether;

[0032] S4, at 70°C, with a power of 600W, ultrasonic for 10min, incubate for 1-2h, then cool to room temperature, to obtain nano-silica modified polycarboxylic acid superplasticizer. Example 4:

[0033] Preparation of nano-silica modified polycarboxylic acid superplasticizer:

[0034] S1, raw materials: methyl alkenyl alcohol polyoxyethylene ether (HPEG), iso-pentenyl alcohol polyoxyethylene ether (TPEG), maleic acid (MA), hydrogen peroxide (w(H2O2) = 27.5%), ascorbic acid (VC), mercaptopropionic acid (MPA), nano-silica (NS), distilled water;

[0035] S2, the acid ether ratio of maleic acid mixed with methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether is 4:1, and the mass concentration of the prepared maleic acid solution is 2%; hydrogen peroxide (w(H2O2) = 27.5%) is prepared into a hydrogen peroxide solution with a mass concentration of 2.6% by using distilled water, wherein the amount of effective component hydrogen peroxide in the hydrogen peroxide is 0.15% of the mass of the mixed methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether; 0.3% of the mass of the mixed methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether is added to mercaptopropionic acid, and ascorbic acid is added, and a mixed solution of mercaptopropionic acid and ascorbic acid is prepared by using distilled water, wherein the content of mercaptopropionic acid in the mixed solution is 0.6%, and the content of ascorbic acid is 1.2%;

[0036] S3, add equal molar ratio of methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether to distilled water, heat and stir uniformly until dissolved to form a mixed solution of methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether, then add hydrogen peroxide solution to the mixed solution of methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether, and then slowly add the mixed solution of maleic acid, mercaptopropionic acid and ascorbic acid, and nano-silica suspension in sequence, wherein the mixed solution of maleic acid, mercaptopropionic acid and ascorbic acid, and nano-silica suspension are added dropwise for 1.5-2 h, 2-3 h and 1.5-2 h respectively, and the amount of nano-silica is 20% of the mass of the mixed methyl allyl alcohol polyoxyethylene ether and isopentenyl alcohol polyoxyethylene ether;

[0037] S4, at 50℃, with a power of 600W, ultrasonic for 20min, and after incubation for 1-2h, cool to room temperature to obtain nano-silica modified polycarboxylic acid water reducer. Example 5:

[0038] Preparation of nano-silica modified polycarboxylic acid water reducer:

[0039] S1, raw materials: methyl allyl alcohol polyoxyethylene ether (HPEG), isopentenyl alcohol polyoxyethylene ether (TPEG), maleic acid (MA), hydrogen peroxide (w(H2O2) = 27.5%), ascorbic acid (VC), mercaptopropionic acid (MPA), nano-silica (NS), distilled water;

[0040] S2, the acid ether ratio of maleic acid mixed with methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 3.5:1, and the maleic acid solution is prepared with distilled water to have a mass concentration of 5%; hydrogen peroxide (w(H2O2) = 27.5%) is prepared with distilled water to have a mass concentration of 2.6%, wherein the amount of effective component hydrogen peroxide in the hydrogen peroxide is 0.25% of the mass of the mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether; 0.35% of the mass of the mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is mercaptopropionic acid, and the mixed solution of mercaptopropionic acid and ascorbic acid is prepared with distilled water, wherein the content of mercaptopropionic acid in the mixed solution is 0.8%, and the content of ascorbic acid is 1.6%;

[0041] S3, equimolar ratio of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is added to distilled water, heated and stirred at a constant speed until it is dissolved, and then the mixed solution of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is formed, and then the hydrogen peroxide solution is added to the mixed solution of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether, and then the mixed solution of maleic acid, the mixed solution of mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are added slowly in sequence, wherein the mixed solution of maleic acid, the mixed solution of mercaptopropionic acid and ascorbic acid, and the nano-silica suspension are added dropwise in 1.5-2 h, 2-3 h and 1.5-2 h respectively, and the amount of nano-silica is 10% of the mass of the mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether;

[0042] S4, at 30°C, with a power of 100W, the tip ultrasonic is 50min, and after 1-2h of incubation, it is cooled to room temperature, and then the nano-silica modified polycarboxylic acid water reducing agent is prepared.

[0043] In order to further observe the changes in structure and performance of the prepared nano-silica modified polycarboxylic acid water reducing agent, the nano-silica modified polycarboxylic acid water reducing agent prepared in the above examples 1-5 is detected by infrared spectrum. Please refer to Figure 1 , Figure 1 The infrared spectrum of the nano-silica modified polycarboxylic acid water reducing agent of example 1 of the present application (the infrared spectrum of examples 2-5 is similar to that of example 1, so it is not listed again), which is known from Figure 1 It can be seen that the nano-silica is stably grafted on the polyoxyethylene ether molecular chain through the silicon-oxygen bond, which can ensure the long-time enhancement effect on the macroscopic properties of cement-based materials, including mechanical properties and working properties.

[0044] The present application takes the nano-silica modified polycarboxylic acid water reducer prepared without tip ultrasonic as the comparative example of the nano-silica modified polycarboxylic acid water reducer prepared in examples 1-5, and tests and compares the cement paste fluidity under the action of the nano-silica modified polycarboxylic acid water reducer prepared under different ultrasonic conditions. The results show that after introducing the tip ultrasonic, the grafting efficiency and the reaction efficiency of the nano-silica and the water reducer can be effectively improved, and the dispersion effect and the stability of the whole system can be improved.

Claims

1. A process for the preparation of nano-silica modified polycarboxylate superplasticizer by tip sonication, characterized by, The method comprises the following steps: S1, preparing a maleic acid solution and a hydrogen peroxide solution respectively by using distilled water, and preparing a mixed solution of mercaptopropionic acid and ascorbic acid by using distilled water; S2, mixing and dissolving equal molar ratio of methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether in distilled water, then adding the hydrogen peroxide solution, and then adding the maleic acid solution, the mixed solution of mercaptopropionic acid and ascorbic acid, and the nano-SiO2 suspension solution in sequence, and completing the dropping within 1.5-2 h, 2-3 h and 1.5-2 h respectively, and performing tip ultrasonic, wherein the acid-ether ratio of the maleic acid to the mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 2.8-4.4:1, the mass percentage of the mercaptopropionic acid relative to the mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 0.3-0.5%, the mass percentage of the nano-SiO2 relative to the mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 5-30%, the temperature of the tip ultrasonic is 20-70℃, the power is 50-600 W, and the time is 10-120 min; S3, after heat preservation for 1-2 h, cooling to room temperature.

2. The process for preparing nano-silica modified polycarboxylate superplasticizer by tip ultrasonic according to claim 1, characterized in that, The mass percentage of the effective component, hydrogen peroxide, in the hydrogen peroxide relative to the mixed methyl alkenyl alcohol polyoxyethylene ether and iso-pentenyl alcohol polyoxyethylene ether is 0.1-0.3%.

3. The process for preparing nano-silica modified polycarboxylate superplasticizer by tip ultrasonic according to claim 1, characterized in that, The content of the mercaptopropionic acid and ascorbic acid in the mixed solution of the mercaptopropionic acid and ascorbic acid is 0.5-1% and 1-2% respectively.

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