CN112759725A

CN112759725A - Novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and preparation method thereof

Info

Publication number: CN112759725A
Application number: CN202110028650.7A
Authority: CN
Inventors: 关文勋; 程冠之; 董全霄; 谢永江; 夏思盟; 谭盐宾; 翁智财; 冯仲伟; 李享涛; 刘子科; 李书明; 李世达; 谢清清; 李旺; 曹继涛; 栗少清; 舒双炉
Original assignee: Beijing Tiefeng Construction Engineering Technology Co ltd; China Academy of Railway Sciences Corp Ltd CARS; Railway Engineering Research Institute of CARS; China State Railway Group Co Ltd
Current assignee: Beijing Tiefeng Construction Engineering Technology Co ltd; China Academy of Railway Sciences Corp Ltd CARS; Railway Engineering Research Institute of CARS; China State Railway Group Co Ltd
Priority date: 2021-01-11
Filing date: 2021-01-11
Publication date: 2021-05-07
Anticipated expiration: 2041-01-11
Also published as: CN112759725B

Abstract

The invention discloses a preparation method of a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer. The novel mud-resistant slump-retaining nano polycarboxylate superplasticizer is prepared by the following steps: (1) and preparing the anti-mud cross-linking agent. (2) And (4) carrying out polymerization reaction. The novel mud-resistant slump-retaining nano polycarboxylate water reducer with a cross-linking structure is obtained by carrying out emulsion polymerization by using a sulfonate polymerizable emulsifier, a polyether polyol mud-resistant cross-linking agent and a monomer. Through crosslinking hardening of the nano micelle structure, the dispersibility of the water reducer can be improved, and the effects of thickening, viscosity reduction, effective mud resistance and concrete workability improvement can be achieved. Along with the gradual hydrolysis of the nano polycarboxylic acid water reducer in cement paste, the micelle is cracked through the fracture of a cross-linked structure and the change of hydrophilicity and hydrophobicity, and a plurality of mud-resistant small molecules and linear polycarboxylic acid molecules can be released, so that the nano polycarboxylic acid water reducer has a long-term mud-resistant slump-retaining effect. The water reducing agent can also be used as a regulator in machine-made sand concrete.

Description

Novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and preparation method thereof

Technical Field

The invention belongs to the field of high polymer materials, and particularly relates to a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof.

Background

With the rapid increase of the current social development and various engineering construction requirements, the preparation technology and the performance of concrete as one of the most important building engineering materials are continuously developed. The current construction requirements are high for the fluidity and the holding capacity of concrete, and the mineral admixture and the functional admixture which are used in large amount in high-performance concrete also make the fluidity and the holding for a long time more difficult. In addition, because of wide regions in China, obvious change of temperature and humidity along with seasons and large difference of raw materials used for concrete, the phenomenon of insufficient fluidity or over-quick loss often occurs in the processes of mixing and transporting the concrete.

The chemical admixture is one of important guarantees of the performance of high-performance concrete, wherein the polycarboxylic acid water reducing agent has the advantages of low mixing amount, high water reducing rate, good slump retaining performance, low shrinkage rate, large modification potential and the like, is widely applied to concrete configuration, and replaces the traditional lignosulfonate and naphthalene water reducing agents to become main products in the current water reducing agent market. In order to make up for the deficiency of slump retaining performance, a polycarboxylic acid slump retaining agent matched with the slump retaining agent is usually compounded into a polycarboxylic acid additive for use. Conventional polycarboxylic acid admixtures are mixtures of linear polymers with long comb-like branches, with a high amount of carboxylic acid, carboxylate groups and polyether long branches, which can effectively increase and maintain the flow properties of the concrete by dispersion, ionization and subsequent hydrolysis. However, the conventional polycarboxylic acid admixture easily reacts with clay due to its own molecular structure, because the clay has an aluminosilicate mineral with a large specific surface area and a multi-layered structure, which has strong adsorption and intercalation effects with respect to the long-chain branched structure of the polycarboxylic acid admixture. Therefore, the conventional polycarboxylic acid admixture is very sensitive to the mud content in the aggregate, and as the mud content increases, the dispersing performance and slump retaining performance of the polycarboxylic acid admixture are obviously reduced, so that the working performance of concrete is greatly reduced. Nowadays, natural sand resources in China are increasingly exhausted, and machine-made sand aggregate gradually replaces natural sand to become a main construction sand source. Because the production processes and raw material quality of different regions and enterprises are different, the quality fluctuation of the produced machine-made sand aggregate is large, and the problems of powder content, high mud content, more needle-shaped particles and the like are often attached, so that the working performance and the workability of the related concrete are influenced.

Research shows that some special structures or functional groups can be preferentially combined with soil, so that the influence of clay minerals on the polycarboxylic acid admixture is reduced. Patent CN109776742A discloses a phosphate ester-containing anti-mud type polycarboxylate water reducing agent, which can effectively improve the dispersibility in high mud content concrete by copolymerizing unsaturated phosphate ester monomers in a polycarboxylate molecular chain. Patent CN104961377B discloses a method for preparing a polycarboxylic acid water reducing agent by introducing a sacrificial agent containing a large amount of anions, such as a potassium polyacrylate aqueous solution or polyacrylic acid-sodium methallylsulfonate, which can improve the adaptability of the polycarboxylic acid water reducing agent to high-mud-content sand. Patent CN106517857A discloses a special polycarboxylic acid water reducer for high-mud-content system ultra-long slump retaining concrete, which synergistically resists mud by compounding slow-release, slow-setting, slump retaining and organic cationic polymers to prolong slump retaining time.

The mud-resistant admixture prepared by the prior art has unsatisfactory effect and mechanism when used for solving the problem of high mud content, is accompanied by the problems of cost increase, difficult use and unstable effect, and is difficult to produce and apply on a large scale. Therefore, the research of the mud-resistant polycarboxylic acid admixture with higher adaptability has important significance for the whole industry.

Disclosure of Invention

The invention aims to solve the problems and provides a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof.

The novel mud-resistant slump-retaining nano polycarboxylic acid water reducer is a polymer nano micelle with a cross-linking structure, which is synthesized by emulsion polymerization of a polyether macromonomer, unsaturated carboxylic acid, unsaturated carboxylic ester, a styrene monomer, a mud-resistant cross-linking agent and a polymerizable mud-resistant emulsifying agent, wherein the mud-resistant cross-linking agent is at least one of polyfunctional monomers obtained by esterification reaction of polyether polyol and unsaturated anhydride, and the dosage of the mud-resistant cross-linking agent is 2-8% of the total amount of the monomers.

The polyether macromonomer: unsaturated carboxylic acid: unsaturated carboxylic acid ester: the molar ratio of the styrene monomers is 1: (1-5): (4-12): (1-8).

The polyether macromonomer is at least one of isobutylene polyglycol ether (HPEG), prenol polyglycol ether (TPEG), Allyl Polyglycol Ether (APEG) and ethylene glycol monovinyl Ether Polyoxyethylene Ether (EPEG) with the molecular weight of 1600-4000, the unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, fumaric acid and itaconic acid, the unsaturated carboxylic acid ester is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxypropyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate, and the styrene monomer is at least one of styrene, p-chloro methyl styrene, 4-methyl styrene and alpha-methyl styrene.

The polymerizable anti-mud emulsifier has a molecular structure of

N is 7-15, and the amount of n is 1-2% of the amount of the monomer.

The polyether polyol is at least one of polymer polyol, polyoxyethylene polyol, polyoxypropylene polyol, polytetrahydrofuran polyol and copolyether polyol with the molecular weight of 600-7000, and the unsaturated anhydride is at least one of acrylic anhydride, methacrylic anhydride, maleic anhydride and itaconic anhydride.

The preparation method of the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer comprises the following steps:

(1) preparing an anti-mud cross-linking agent: and (2) carrying out esterification reaction on polyether polyol and unsaturated anhydride in a solvent added with a polymerization inhibitor under the action of a catalyst to obtain the multifunctional polyether anti-mud crosslinking agent.

(2) Polymerization reaction: adding most of initiator, polymerizable anti-mud emulsifier molecules and water into a reaction container, starting stirring to gradually dissolve an emulsifier, then adding part of mixed small monomers and a chain transfer agent, stirring to fully emulsify the mixture, then adding part of initiator solution, heating a reaction system to 75-85 ℃, dropwise adding the rest of mixed small monomers, chain transfer agent and all polyether large monomer solutions into the reaction container after reaction liquid is light blue, dropwise adding the rest of mixed small monomers, chain transfer agent and all polyether large monomer solutions into the reaction container for 1-3 hours, dropwise adding the cross-linking agent solution synthesized in the step (1) into the reaction container after dropwise adding is completed, keeping the temperature for 1 hour after the dropwise adding of the cross-linking agent is completed, slowly adding the rest of initiator, heating to 85-95 ℃, and reacting for 1-2 hours to obtain a polymerization product emulsion. And adding a proper amount of alkali into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

In the step (1), the molar ratio of the polyether polyol to the unsaturated anhydride is 1: (2.5-5), the reaction temperature is 40-60 ℃, the reaction time is 5-7 h, the solvent is one or a mixture of pyridine, N-dimethylformamide and dimethyl sulfoxide, the polymerization inhibitor is at least one of DPPH, hydroquinone, p-tert-butyl catechol or phenothiazine, the dosage is 0.1-2% of the total amount of reactants, and the catalyst is 4-dimethylaminopyridine, benzenesulfonic acid or p-toluenesulfonic acid, and the dosage is 0.5-5% of the mass of the reactants.

In the step (2), the chain transfer agent is at least one of mercaptoethanol, mercaptoacetic acid, mercaptopropionic acid, mercaptopropanol, sodium hypophosphite, trisodium phosphate and CTA1420, the dosage of the chain transfer agent is 0.2-2% of the dosage of the monomer, the initiator is at least one of potassium persulfate, ammonium persulfate, azodiisopropyl amidine hydrochloride, azodiisobutymidine dihydrochloride, a hydrogen peroxide-ascorbic acid initiation system, a hydrogen peroxide-rongalite initiation system and an ammonium persulfate-sodium sulfite initiation system, the dosage of the chain transfer agent is 0.3-3% of the dosage of the monomer, and the alkali is at least one of sodium hydroxide, potassium hydroxide, triethylamine and triethanolamine or an aqueous solution thereof.

The novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and the preparation method thereof have the positive effects that:

compared with the existing polycarboxylic acid water reducing agent, the novel nano polycarboxylic acid water reducing agent prepared by the method has the advantages of good dispersing effect, high slump retaining effect, strong and lasting mud resisting effect, and good viscosity reducing and thickening effects on concrete with high viscosity, such as high-grade concrete, machine-made sand concrete with high powder content and the like. The novel nano polycarboxylate water reducer can be used independently, and can also be compounded with at least one of the existing known sulfamic acid, lignin and polycarboxylate water reducers for use, so that the slump retaining capability and the mud resistance of the existing water reducer product and the adaptability of machine-made sand aggregate are improved.

The novel nano water reducing agent is self-assembled into a nano micelle structure through amphiphilic polycarboxylic acid molecules, so that the steric effect is increased, the intercalation effect in the layered structure of clay minerals is effectively reduced, and the sensitivity of the novel nano water reducing agent to the mud content of aggregate is greatly reduced. Meanwhile, the soft nano-micelle is fixed to be hard nano-particles through the cross-linked structure, so that the condition that the micelle is dissolved and dissociated due to the fact that the emulsion is diluted by a large amount of mixing water in the using process is avoided, and on the other hand, the hard nano-particles dispersed in the slurry can play a good internal lubricating role and can play a role in thickening, viscosity reduction and adjustment and workability. The ester group in the cross-linking agent and the amide group in the mud-resistant emulsifier can be gradually hydrolyzed and broken under the alkaline condition of concrete, so that the cross-linking structure is broken and the polyether polyol and sulfonate mud-resistant agent is released, thereby playing a role in resisting mud for a long time. And along with the fracture of the cross-linked structure and the gradual hydrolysis of ester groups in the polycarboxylic acid molecular chain into carboxylate radicals, the hydrophilicity and the dispersing performance of the polycarboxylic acid molecular chain are enhanced, the micelle is gradually dissociated, and a large number of linear polycarboxylic acid molecules are released to play a role in dispersing and reducing water, so that the long-time fluidity maintenance is realized. And the synergistic effect exists among different kinds of anti-mud crosslinking agents, the effects of inhibiting clay intercalation and resisting expansion in a long time can be achieved through the synergistic crosslinking adjustment of the crosslinking agents with the types and the dosage, and the continuous mud-resistant slump-retaining performance of the concrete can be effectively improved under special conditions of low temperature, high mud content and the like. Through the comprehensive effect of various reasons, the nano water reducing agent has excellent dispersing, slump retaining and mud resisting performances, and can effectively improve the continuous working performance of concrete in the mixing, transporting and pumping processes.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

Example 1: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent A: 24g of polyoxyethylene glycol with the molecular weight of 600, 15g of acrylic anhydride, 0.3g of hydroquinone and 0.6g of p-toluenesulfonic acid are added into a reaction bottle containing 70g of pyridine to be stirred and dissolved, after the mixture is completely dissolved, the temperature is raised to 50 ℃ under the protection of nitrogen to carry out esterification reaction for 6 hours, and after the reaction is finished, the anti-mud crosslinking agent A is obtained through dialysis separation;

(2) polymerization reaction: adding 2g of polymerizable anti-mud emulsifier and 120g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40% of a mixture of small monomers and a chain transfer agent (containing 10g of acrylic acid, 10g of hydroxypropyl acrylate, 40g of butyl acrylate, 20g of styrene and 1.8g of mercaptoethanol) into the solution, stirring to fully emulsify the mixture, then adding 1.8g of ammonium persulfate, heating the reaction system to 75 ℃, dropwise adding the rest of the mixture of small monomers and the chain transfer agent and a polyether large monomer solution (containing 100g of isopentenol polyethylene glycol ether with the molecular weight of 2400 and 80g of water) into the reaction container after the reaction solution presents a light blue emulsion for 2 hours, dropwise adding water-soluble droplets containing 8g of anti-mud cross-linking agent A into the reaction container after dropwise adding is completed, dropwise adding for 30 minutes, then preserving heat for 1 hour, and slowly adding 0.5g of ammonium persulfate, heating to 85 ℃ and reacting for 1h to obtain the emulsion of the polymerization product. And then adding 30% sodium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Example 2: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent B: adding 40g of polyoxypropylene diol with the molecular weight of 1000, 12g of maleic anhydride, 0.5g of phenothiazine and 1g of benzenesulfonic acid into a reaction bottle containing 80g N, N-dimethylformamide, stirring for dissolving, heating to 45 ℃ under the protection of nitrogen after completely dissolving, carrying out esterification reaction for 8 hours, and obtaining an anti-mud crosslinking agent B after the reaction is finished and dialysis separation;

(2) polymerization reaction: adding 1.8g of polymerizable anti-mud emulsifier and 120g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40 percent of a mixture of small monomers and a chain transfer agent (containing 4g of methacrylic acid, 12g of hydroxyethyl acrylate, 30g of methyl methacrylate, 30g of p-chloromethyl styrene and 2g of mercaptopropionic acid) into the solution, stirring to fully emulsify the mixture, then adding 1.5g of potassium persulfate, heating the reaction system to 80 ℃, after the reaction liquid presents light blue emulsion, dropwise adding the rest mixture of small monomers and the chain transfer agent and a polyether macromonomer solution (containing 100g of isobutenol polyglycol ether with the molecular weight of 2400 and 80g of water) into the reaction container for 1.5 hours, adding 4g of anti-mud crosslinking agent B into the reaction container after dropwise adding, dropwise adding for 40 minutes, and then keeping the temperature for 1 hour, slowly adding 0.5g of potassium persulfate, heating to 85 ℃, and reacting for 1 hour to obtain a polymerization product emulsion. And then adding 30% potassium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Example 3: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent B: same as example 2, step (1);

(2) polymerization reaction: adding 1.8g of polymerizable anti-mud emulsifier and 120g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40 percent of a mixture of small monomers and a chain transfer agent (containing 4g of methacrylic acid, 12g of hydroxyethyl acrylate, 30g of methyl methacrylate, 30g of p-chloromethyl styrene and 2g of mercaptopropionic acid) into the solution, stirring to fully emulsify the mixture, then adding 1.5g of potassium persulfate, heating the reaction system to 80 ℃, after the reaction liquid presents light blue emulsion, dropwise adding the rest mixture of small monomers and the chain transfer agent and a polyether macromonomer solution (containing 100g of isobutenol polyglycol ether with the molecular weight of 2400 and 80g of water) into the reaction container for 1.5 hours, adding 13g of anti-mud crosslinking agent B into the reaction container after dropwise adding, dropwise adding for 40 minutes, and then keeping the temperature for 1 hour, slowly adding 0.5g of potassium persulfate, heating to 85 ℃, and reacting for 1 hour to obtain a polymerization product emulsion. And then adding 30% potassium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Example 4: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent C: adding 60g of polytetrahydrofuran diol with the molecular weight of 2400, 12g of methacrylic anhydride, 0.5g of DPPH and 0.6g of 4-dimethylaminopyridine into a reaction bottle containing 100g of pyridine, stirring for dissolving, heating to 55 ℃ under the protection of nitrogen after completely dissolving, carrying out esterification reaction for 6 hours, and obtaining the anti-mud crosslinking agent C through dialysis separation after the reaction is finished;

(2) polymerization reaction: adding 2.5g of polymerizable anti-mud emulsifier and 100g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40 percent of a mixture of small monomers and a chain transfer agent (containing 3g of acrylic acid, 5g of fumaric acid, 12g of butyl acrylate, 32g of methyl methacrylate, 30g of 4-methyl styrene and 1.3g of thioglycolic acid) into the solution, stirring to fully emulsify the mixture, then adding 2g of azodiisopropyl amidine hydrochloride, heating the reaction system to 82 ℃, after the reaction liquid presents light blue emulsion, dropwise adding the rest mixture of the small monomers and the chain transfer agent and a polyether type large monomer solution (containing 140g of prenol polyethylene glycol ether with the molecular weight of 3600 and 100g of water) into the reaction container for 2.5 hours, dropwise adding 10g of anti-mud crosslinking agent C into the reaction container after the dropwise adding is completed, and dropwise adding water for 45 minutes, then preserving the heat for 1h, slowly adding 0.6g of azodiisopropyl amidine oxazoline hydrochloride, heating to 90 ℃ and reacting for 1h to obtain the emulsion of the polymerization product. And then adding 30% sodium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Example 5: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent D: adding 65g of polyoxyethylene triol with the molecular weight of 3000, 15g of itaconic anhydride, 0.6g of p-tert-butyl catechol and 1.4g of 4-dimethylaminopyridine into a reaction bottle containing 100g of dimethyl sulfoxide, stirring for dissolving, heating to 60 ℃ under the protection of nitrogen after complete dissolution, carrying out esterification reaction for 6h, and obtaining an anti-mud crosslinking agent D after the reaction is finished and through dialysis separation;

(2) polymerization reaction: adding 3g of polymerizable anti-mud emulsifier and 100g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40 percent of a mixture of small monomers and a chain transfer agent (containing 4g of acrylic acid, 4g of itaconic acid, 10g of methyl acrylate, 30g of butyl acrylate, 10g of hydroxybutyl methacrylate, 25g of alpha-methyl styrene and 25g of CTA-14201.5 g) into the solution, stirring to fully emulsify the mixture, then adding 1.8g of potassium persulfate, heating the reaction system to 80 ℃, after the reaction liquid presents light blue emulsion, dropwise adding the rest mixture of the small monomers and the chain transfer agent and a polyether large monomer solution (containing 120g of isobutenol polyglycol ether with the molecular weight of 3000 and 100g of water) into the reaction container for 2 hours, and adding 9g of water-soluble droplets containing the anti-mud cross-linking agent D into the reaction container after dropwise adding is completed, the dropping time is 35min, then the temperature is kept for 1h, 0.6g of potassium persulfate is slowly added, the temperature is raised to 85 ℃ and the reaction is carried out for 1h, thus obtaining the polymer emulsion. And then adding 30% potassium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Example 6: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent D: same as example 5, step (1);

Example 7: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent A: same as example 1, step (1);

(2) preparing an anti-mud cross-linking agent D: same as example 5, step (1);

(3) polymerization reaction: adding 2g of polymerizable anti-mud emulsifier and 120g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40% of a mixture of small monomers and a chain transfer agent (containing 10g of acrylic acid, 10g of hydroxypropyl acrylate, 40g of butyl acrylate, 20g of styrene and 1.8g of mercaptoethanol) into the solution, stirring to fully emulsify the mixture, then adding 1.8g of ammonium persulfate, heating the reaction system to 75 ℃, dropwise adding the rest of the mixture of small monomers and the chain transfer agent and a polyether large monomer solution (containing 100g of isopentenol polyethylene glycol ether with the molecular weight of 2400 and 80g of water) into the reaction container after the reaction solution is in a light blue emulsion, dropwise adding water solution containing 4g of anti-mud cross-linking agent A and 4g of anti-mud cross-linking agent D into the reaction container for 2 hours, dropwise adding water solution containing 4g of anti-mud cross-linking agent A and 4g of anti-mud cross-linking agent D for 30 minutes, then 0.5g of ammonium persulfate is slowly added, and the temperature is raised to 85 ℃ to react for 1h, thus obtaining the emulsion of the polymerization product. And then adding 30% sodium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Example 8: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent A: same as example 1 step (1)

(2) Preparing an anti-mud cross-linking agent E: adding 80g of polyoxypropylene triol with the molecular weight of 4000, 15g of acrylic anhydride, 0.7g of hydroquinone and 1.5g of p-toluenesulfonic acid into a reaction bottle containing 100g of pyridine, stirring for dissolving, heating to 60 ℃ under the protection of nitrogen after complete dissolution for esterification reaction for 8 hours, and obtaining the anti-mud crosslinking agent E through dialysis separation after the reaction is finished;

(3) polymerization reaction: adding 1.6g of polymerizable anti-mud emulsifier and 80g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40 percent of a mixture of a small monomer and a chain transfer agent (containing 3g of acrylic acid, 3g of methacrylic acid, 25g of butyl methacrylate, 25g of styrene and 3g of trisodium phosphate) into the solution, stirring to fully emulsify the mixture, then adding 1.5g of ammonium persulfate, heating the reaction system to 75 ℃, after the reaction solution presents light blue emulsion, dropwise adding the rest mixture of the small monomer and the chain transfer agent and a polyether large monomer solution (containing 20g of isobutenol polyglycol ether with the molecular weight of 1600, 80g of isopentenol polyglycol ether with the molecular weight of 3000 and 100g of water) into the reaction container for 2 hours, dropwise adding water-soluble liquid containing 6g of anti-mud cross-linking agent A and 6g of anti-mud cross-linking agent E into the reaction container after dropwise adding is finished, the dropping time is 45min, then the temperature is kept for 1h, 0.5g of ammonium persulfate is slowly added, the temperature is raised to 85 ℃ and the reaction is carried out for 1h, thus obtaining the emulsion of the polymerization product. And then regulating the pH value of triethanolamine to be about 6, and then regulating the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Example 9: a novel mud-resistant slump-retaining nano polycarboxylic acid water reducer and a preparation method thereof are as follows

(1) Preparing an anti-mud cross-linking agent C: same as example 3, step (1);

(2) preparing an anti-mud cross-linking agent F: adding 80g of polytetrahydrofuran triol with the molecular weight of 5000, 14g of acrylic anhydride, 0.3g of DPPH and 1.6g of 4-dimethylaminopyridine into a reaction bottle containing 100g of pyridine, stirring for dissolving, heating to 60 ℃ under the protection of nitrogen after completely dissolving, carrying out esterification reaction for 8 hours, and obtaining an anti-mud crosslinking agent F through dialysis separation after the reaction is finished;

(3) polymerization reaction: adding 1.8g of polymerizable anti-mud emulsifier and 100g of water into a reaction vessel, starting stirring to dissolve the emulsifier, then adding 40% of a mixture of a small monomer and a chain transfer agent (containing 4g of acrylic acid, 2g of fumaric acid, 2g of itaconic acid, 25g of methyl methacrylate, 26g of 4-methylstyrene and 1.5g of mercaptopropanol) into the solution, stirring to fully emulsify the mixture, then adding 2g of azobisisobutyramidine dihydrochloride, heating the reaction system to 82 ℃, dropwise adding the rest of the mixture of the small monomer and the chain transfer agent and a polyether type large monomer solution (containing 40g of allyl polyglycol ether with the molecular weight of 2400, 60g of isopentenol polyglycol ether with the molecular weight of 4000 and 100g of water) into the reaction vessel for 2.5 hours after the reaction solution is in a light blue emulsion, dropwise adding water solution containing 8g of anti-mud cross-linking agent C and 5g of anti-mud cross-linking agent F into the reaction vessel, the dropping time is 30min, then the temperature is kept for 1h, 0.6g of azobisisobutyramidine dihydrochloride is slowly added, the temperature is raised to 90 ℃ and the reaction is carried out for 1h, thus obtaining the emulsion of the polymerization product. And adding triethylamine into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-slump-resistant nano polycarboxylic acid water reducer.

Comparative example 1: conventional linear polycarboxylic acid water reducing agent

Adding 100g of isobutylene polyglycol ether with the molecular weight of 2400 into a reaction bottle containing 90g of water, uniformly stirring, adding 1g of hydrogen peroxide, uniformly stirring, dropwise adding a polymerization monomer solution (containing 10g of acrylic acid, 8g of hydroxypropyl acrylate and 20g of water) and a reducing agent solvent (containing 0.5g of ascorbic acid, 1g of mercaptopropionic acid and 30g of water) into the reaction container for reaction, wherein the reaction starting temperature is 25 ℃, the dropwise adding time is 2 hours and 2.5 hours respectively, and preserving heat for 2.5 hours after the dropwise adding is finished to obtain a copolymerization product. Adding 35 percent of sodium hydroxide aqueous solution by mass fraction to neutralize until the pH value is about 6, thus obtaining the conventional linear polycarboxylate superplasticizer.

Comparative example 2: synthesis of conventional nano emulsion water reducing agent

Adding 1.8g of sodium dodecyl benzene sulfonate and 100g of water into a reaction container, stirring to dissolve the sodium dodecyl benzene sulfonate and the water, then adding 40% of a mixture of a small monomer and a chain transfer agent (containing 12g of acrylic acid, 40g of butyl acrylate, 10g of styrene and 1.5g of mercaptopropanol) into the solution, stirring to fully emulsify the mixture, then adding 2g of potassium persulfate, heating the reaction system to 82 ℃, after the reaction liquid presents a light blue emulsion, dropwise adding the rest mixture of the small monomer and the chain transfer agent and a polyether large monomer solution (containing 105g of prenyl alcohol glycol ether with the molecular weight of 2400 and 80g of water) into the reaction container, dropwise adding the mixture for 2.5 hours, then keeping the temperature for 1.5 hours, slowly adding 0.6g of potassium persulfate, heating to 90 ℃ and reacting for 1 hour to obtain a polymerization product emulsion. And then adding 30% sodium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to the required value to obtain the nano polycarboxylic acid water reducing agent.

Comparative example 3: anti-mud nano polycarboxylic acid water reducing agent

(1) Preparing an anti-mud cross-linking agent B: same as example 2, step (1);

(2) polymerization reaction: adding 1.8g of polymerizable anti-mud emulsifier and 120g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40 percent of a mixture of small monomers and a chain transfer agent (containing 4g of methacrylic acid, 12g of hydroxyethyl acrylate, 30g of methyl methacrylate, 30g of p-chloromethyl styrene and 2g of mercaptopropionic acid) into the solution, stirring to fully emulsify the mixture, then adding 1.5g of potassium persulfate, heating the reaction system to 80 ℃, after the reaction liquid presents light blue emulsion, dropwise adding the rest mixture of small monomers and the chain transfer agent and a polyether macromonomer solution (containing 100g of isobutenol polyglycol ether with the molecular weight of 2400 and 80g of water) into the reaction container for 1.5 hours, adding 2g of water solution containing the anti-mud crosslinking agent B into the reaction container after dropwise adding is completed, dropwise adding for 40 minutes, and then keeping the temperature for 1 hour, slowly adding 0.5g of potassium persulfate, heating to 85 ℃, and reacting for 1 hour to obtain a polymerization product emulsion. And then adding 30% potassium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Comparative example 4: anti-mud nano polycarboxylic acid water reducing agent

(1) Preparing an anti-mud cross-linking agent B: same as example 2, step (1);

(2) polymerization reaction: adding 1.8g of polymerizable anti-mud emulsifier and 120g of water into a reaction container, starting stirring to dissolve the emulsifier, then adding 40 percent of a mixture of small monomers and a chain transfer agent (containing 4g of methacrylic acid, 12g of hydroxyethyl acrylate, 30g of methyl methacrylate, 30g of p-chloromethyl styrene and 2g of mercaptopropionic acid) into the solution, stirring to fully emulsify the mixture, then adding 1.5g of potassium persulfate, heating the reaction system to 80 ℃, after the reaction liquid presents light blue emulsion, dropwise adding the rest mixture of small monomers and the chain transfer agent and a polyether macromonomer solution (containing 100g of isobutenol polyglycol ether with the molecular weight of 2400 and 80g of water) into the reaction container for 1.5 hours, adding 16g of water solution containing the anti-mud crosslinking agent B into the reaction container after dropwise adding is completed, dropwise adding for 40 minutes, and then keeping the temperature for 1 hour, slowly adding 0.5g of potassium persulfate, heating to 85 ℃, and reacting for 1 hour to obtain a polymerization product emulsion. And then adding 30% potassium hydroxide solution into the emulsion, adjusting the pH value to be about 6, and adjusting the solid content to be required to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

Description of the effects:

the clean slurry flow is measured by using the novel mud-resistant slump-retaining nano polycarboxylate superplasticizer and a conventional polycarboxylate superplasticizer according to GB/T8077-2012 'concrete admixture homogeneity test method', and cement is taken as reference cement. The test results are shown in Table 1.

TABLE 1 Cement paste fluidity test results

"/" is no flow capability.

As can be seen from the data in Table 1, under the condition of the same water reducing agent and montmorillonite mixing amount, the initial fluidity and the fluidity retention performance of the example (the novel mud-resistant slump-retaining nano polycarboxylic acid water reducing agent in the invention) are better than those of the comparative example, especially the fluidity retention capacity under the condition of high mud content, and the neat pastes prepared in comparative examples 1-4 are greatly reduced along with time and lose the fluidity performance after 60min or 90 min. Compared with the prior art, the examples 1 to 9 have better fluidity in 120min, which shows that the novel mud-resistant slump-retaining nano polycarboxylate water reducer crosslinked by the mud-resistant crosslinking agent in a proper dosage range has excellent dispersing performance and long-term mud-resistant slump-retaining performance under the condition of high mud content, and the conventional linear polycarboxylate water reducer, the conventional nano polycarboxylate water reducer and the mud-resistant nano polycarboxylate water reducer with the dosage exceeding a limited range have relatively poor performance.

It can be seen from the table that different crosslinking monomers have a certain synergistic effect, and the outgoing flow and the flow retention performance of example 7 using 50% of the anti-mud crosslinking agent a and 50% of the anti-mud crosslinking agent D are significantly better than those of example 1 using the anti-mud crosslinking agent a alone and example 6 using the anti-mud crosslinking agent D alone. This is caused by the multistage crosslinking of monomers of different functionality. It can be seen from the overall results that the use effect of the multiple cross-linked examples 7 to 9 is better than that of the single cross-linked examples 1 to 6.

To further study this synergistic effect, we measured the net slurry flow according to GB/T8077-. The test results are shown in Table 2.

TABLE 2 Net slurry test results at Low temperature conditions

It can be seen that under the condition of low temperature and high mud content, the effect of the embodiment 1 and the embodiment 6 which are independently crosslinked is obviously reduced, the fluidity at 120min is very small, while the embodiment 7 which is subjected to multi-stage crosslinking still has better performance, and the better fluidity can still be maintained at 120 min. It can thus be seen that this synergistic effect between the multiple cross-linking agents is more pronounced at low temperature conditions.

The novel mud-resistant slump-retaining nano polycarboxylate water reducer and the conventional polycarboxylate water reducer are respectively used in C30 concrete internally doped with montmorillonite for testing. The concrete mixture performance test is carried out according to GB/T50080-2002 Standard for Performance test methods of common concrete mixtures, and slump and expansion of the concrete mixture are tested for 60 min. The mixing proportion of the C30 concrete is shown in Table 3. The concrete test results are shown in Table 4.

TABLE 3C 30 concrete mixing ratio

Cement	Fly ash	River sand	Crushing stone	Water (W)	Additive agent
						300	80	820	1086	165	1%

TABLE 4 concrete test results

As can be seen from the data in Table 4, the concrete used in C30 in the examples 1-8 has good fluidity and dispersibility, has long-term slump retaining and mud resisting performance, and the performance comparison is obviously superior to that of the comparative examples 1-4.

The novel mud-resistant slump-retaining nano polycarboxylate superplasticizer can not be completely used in the conventional machine-made sand concrete with higher powder content, and the flow property and slump-retaining property of the machine-made sand concrete can be effectively improved by compounding a small amount of the mud-resistant slump-retaining nano polycarboxylate superplasticizer with the conventional water reducer. The examples 1 and 7 and the commercially available slump loss resistant water reducer BT in the embodiment are compounded with the commercially available conventional water reducer PCE, and the obtained mixture is respectively used in C30 machine-made sand concrete to test the performance improvement of the conventional water reducer. The concrete mixture performance test is carried out according to GB/T50080-2002 standard of common concrete mixture performance test method, and slump and expansion of the concrete mixture are tested for 60min and 120 min. The mixing proportion of the C30 machine-made sand concrete is shown in Table 5. The fineness modulus of the machine-made sand was 2.9, the stone powder content was 9%, the MB value was 1.8, and the concrete test results are shown in Table 6.

TABLE 5C 30 machine-made Sand concrete mix proportion

TABLE 6 concrete test results

As can be seen from the data in Table 6, the effects of the three water reducing agents are better along with the increase of the mixing amount, the examples 1 and 7 have better effects under the mixing amount of 0.02 percent, the BT mother liquor has poorer effects under the mixing amount of 0.02 percent, and the concrete fluidity and the working performance of the examples 1 and 7 are obviously better than those of the commercial BT slump retaining agent under the same dosage.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are within the scope of the present invention without departing from the technical spirit of the present invention.

Claims

1. The novel mud-resistant slump-retaining nano polycarboxylic acid water reducer is characterized in that a polymer nano latex with a cross-linking structure is synthesized by a polyether macromonomer, unsaturated carboxylic acid, unsaturated carboxylic ester, a styrene monomer, a mud-resistant cross-linking agent and a polymerizable mud-resistant emulsifying agent through emulsion polymerization, wherein the mud-resistant cross-linking agent is at least one of polyfunctional monomers obtained by esterification reaction of polyether polyol and unsaturated anhydride, and the using amount of the mud-resistant cross-linking agent is 2-8% of the total amount of the monomers.

2. The novel mud and slump resistant nano polycarboxylic acid water reducer as claimed in claim 1, wherein the polyether macromonomer: unsaturated carboxylic acid: unsaturated carboxylic acid ester: the molar ratio of the styrene monomers is 1: (1-5): (4-12): (1-8).

3. The novel mud and slump loss resistant nano polycarboxylic acid water reducer as claimed in claim 1, wherein the polyether macromonomer is at least one of isobutylene glycol polyethylene glycol ether (HPEG), isopentenol polyethylene glycol ether (TPEG), allyl polyethylene glycol ether (APEG), and ethylene glycol monovinyl Ether Polyoxyethylene Ether (EPEG) with molecular weight of 1600-4000, the unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, fumaric acid, and itaconic acid, the unsaturated carboxylic acid is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxypropyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the styrene monomer is at least one of styrene, p-chloromethyl styrene, p-methyl styrene, p-vinyl-styrene, n-vinyl-polyoxyethylene, p-vinyl-acrylate, 4-methyl styrene and/or alpha-methyl styrene.

4. The novel mud and slump loss resistant nano polycarboxylate water reducer as claimed in claim 1, wherein the molecular structure of the polymerizable mud resistant emulsifier is

N is 7-15, and the amount of n is 1-2% of the amount of the monomer.

5. The novel mud and slump loss resistant nano polycarboxylic acid water reducer as claimed in claim 1, wherein the polyether polyol is at least one of polymer polyol, polyoxyethylene polyol, polyoxypropylene polyol, polytetrahydrofuran polyol and copolyether polyol thereof with molecular weight of 600-7000, and the unsaturated anhydride is at least one of acrylic anhydride, methacrylic anhydride, maleic anhydride and itaconic anhydride.

6. The preparation method of the novel mud and slump loss resistant nano polycarboxylic acid water reducer as claimed in claims 1-5, is characterized by comprising the following steps:

(1) preparing an anti-mud cross-linking agent: carrying out esterification reaction on polyether polyol and unsaturated anhydride in a solvent added with a polymerization inhibitor under the action of a catalyst to obtain a multifunctional polyether anti-mud crosslinking agent;

(2) polymerization reaction: adding most of initiator, polymerizable anti-mud emulsifier molecules and water into a reaction container, starting stirring to gradually dissolve the emulsifier, then adding part of mixed small monomers and chain transfer agent, stirring to fully emulsify, then adding part of initiator solution, heating the reaction system to 75-85 ℃, and after the reaction liquid is light blue, dropwise adding the rest small mixed monomer, chain transfer agent and all polyether macromonomer solution into a reaction container, the dripping time is 1-3 h, the cross-linking agent solution synthesized in the step (1) is dripped into a reaction container after the dripping is finished, and (3) after the dropwise addition of the cross-linking agent, preserving heat for 1h, slowly adding the rest of initiator, heating to 85-95 ℃, reacting for 1-2 h to obtain a polymerization product emulsion, then adding a proper amount of alkali into the emulsion, adjusting the pH value to be about 6, and then adjusting the solid content to obtain the novel mud-resistant slump-retaining nano polycarboxylic acid water reducer.

7. The process according to claim 6, characterized in that the polyether polyol to unsaturated anhydride molar ratio in step (1) is 1: (2.5-5), the reaction temperature is 40-60 ℃, the reaction time is 5-7 h, the solvent is one or a mixture of pyridine, N-dimethylformamide and dimethyl sulfoxide, the polymerization inhibitor is at least one of DPPH, hydroquinone, p-tert-butyl catechol or phenothiazine, the dosage is 0.1-2% of the total amount of reactants, and the catalyst is 4-dimethylaminopyridine, benzenesulfonic acid or p-toluenesulfonic acid, and the dosage is 0.5-5% of the mass of the reactants.

8. The method of claim 6, wherein in step (2), the chain transfer agent is at least one of mercaptoethanol, mercaptoacetic acid, mercaptopropionic acid, mercaptopropanol, sodium hypophosphite, trisodium phosphate and CTA1420, the amount of the chain transfer agent is 0.2-2% of the amount of the monomer, the initiator is at least one of potassium persulfate, ammonium persulfate, azodiisopropylamidine hydrochloride, azodiisobutyamidine dihydrochloride, a hydrogen peroxide-ascorbic acid initiation system, a hydrogen peroxide-rongalite initiation system and an ammonium persulfate-sodium sulfite initiation system, the amount of the chain transfer agent is 0.3-3% of the amount of the monomer, and the base is at least one of sodium hydroxide, potassium hydroxide, triethylamine and triethanolamine or an aqueous solution thereof.

9. The use of the novel mud-resistant nano polycarboxylic acid water reducer prepared by the method in claim 1 as a water reducer, an additive, a mud-resistant clay component or a machine-made sand concrete regulator.