Amphoteric polyfunctional group water reducing agent as well as preparation method and application thereof

Abstract

The invention provides an amphoteric polyfunctional group water reducing agent and a preparation method and application thereof, and the water reducing agent is obtained by carrying out polymerization reaction on a monomer A, a monomer B and a macromonomer P, then carrying out acylation reaction on a polymerization intermediate and halogenated carboxylic ester, and subsequently introducing phosphorus trichloride to carry out phosphonation modification. The monomer A is acrylate; the monomer B is alkenyl imidazole; the macromonomer P is an ether type polyoxyalkylene ether macromonomer containing double-bond end groups, the chain segment units of the macromonomer P are composed of ethylene oxide residues, and the total number of the chain segment units is 15-150. According to the water reducer, on the basis of a technical route of first polymerization and second modification, imidazolyl is introduced into a main chain, and then carboxylic acid and phosphonic acid modification is performed respectively, so that the novel water reducer containing various types of functional groups with different activities, such as conjugated cationic groups, carboxylic acid groups, diphosphonic acid groups and the like, is obtained. The water reducing agent has good adaptability and dispersing capacity to a novel gelling system.

Description

Technical Field

[0001] This invention relates to the field of concrete admixtures, specifically to an amphoteric multifunctional water-reducing agent, its preparation method, and its application. Background Technology

[0002] High-performance water-reducing agents are one of the core admixtures in building materials. Polycarboxylate superplasticizers, in particular, have become indispensable key admixtures in the production of high-performance building materials. With the green and low-carbon transformation of the entire building materials industry, the form of concrete cementitious systems is also quietly changing. Currently, high-admixture low-carbon concrete, represented by the calcined clay-limestone powder-cement (LC3) cementitious system, has attracted much attention. Compared with traditional systems, this type of cementitious system significantly reduces cement usage, which is beneficial for reducing related cement production energy consumption and carbon emissions. However, due to the differences in the physicochemical properties of admixtures and cement, and the influence of high admixture dosage, polycarboxylate superplasticizers in this type of cementitious system often exhibit prominent problems such as decreased dispersion efficiency, poor system viscosity, and poor workability due to the large amount of non-cement cementitious materials and clay derivatives present. Innovative design of the polycarboxylate superplasticizer structure to solve these problems will undoubtedly contribute to the green and low-carbon transformation trend of the building materials industry.

[0003] Existing technologies typically improve performance by introducing functional groups such as quaternary ammonium groups and phosphonic acid groups, but these still suffer from drawbacks such as low monomer polymerization activity and limited group types. For example, patent CN202111580295.0 discloses "a quaternary ammonium salt functional monomer and its preparation method, and a highly adaptable polycarboxylate superplasticizer and its preparation method." This patented technology introduces amphoteric quaternary ammonium and phosphonic acid functional groups into the polycarboxylate backbone, but the double bond group in this monomer is allyl, resulting in poor polymerization activity. Patent CN202210141946.4 discloses "a highly dispersed polycarboxylate superplasticizer." This superplasticizer uses sulfonates and phosphonates as anchoring groups, exhibiting good affinity, but its technical route and group type are still relatively conventional. Patent CN201911340925.X discloses "a low-sensitivity ultra-early strength polycarboxylate superplasticizer and its preparation method," which prepares positively charged monomers based on Michael addition and introduces them into the polycarboxylate chain. However, this patent also uses allyl monomers as initiators, limiting its activity.

[0004] In summary, providing a water-reducing agent that can address the problems in existing technologies that easily lead to decreased dispersion efficiency, poor viscosity, and poor workability in concrete systems is an urgent issue to be solved. Summary of the Invention

[0005] To address the aforementioned deficiencies in existing technologies, this application provides an amphoteric multifunctional water-reducing agent, its preparation method, and its applications. This water-reducing agent is based on a pre-polymerization-modification technology route. By introducing imidazole groups into the main chain and then subjecting it to carboxylic acid and phosphonic acid modifications, a novel water-reducing agent containing various types of functional groups with different activities, including conjugated cationic groups, carboxylic acid groups, and bisphosphonic acid groups, is obtained. This water-reducing agent exhibits good adaptability and dispersibility for novel gelling systems.

[0006] The specific technical solution of this application is as follows:

[0007] A type of amphoteric multifunctional water-reducing agent is characterized by being obtained by polymerization of monomer A, monomer B, and macromonomer P, followed by acylation of the polymerization intermediate with a halocarboxylic acid ester, and then phosphonation modification by introducing phosphorus trichloride.

[0008] Monomer A is an acrylate;

[0009] The monomer B mentioned above is an alkenyl imidazolium;

[0010] The aforementioned macromonomer P is an ether-type polyoxyethylene ether macromonomer containing double-bonded end groups. Its chain segment units are composed of ethylene oxide residues, and the total number of chain segment units is between 15 and 150.

[0011] The molar ratio of monomer A, monomer B, and macromonomer P is (n A +n B ):n P =(2.0~6.0):1,n A :n B =(1-9):1;

[0012] The above-mentioned molar amount of halocarboxylic acid ester is 0.8 to 1.05 times the molar amount of imidazole group in the polymer intermediate;

[0013] The above-mentioned molar amount of phosphorus trichloride is 0.6 to 1.8 times the molar amount of imidazole group in the polymer intermediate, and not more than twice the molar amount of halocarboxylic acid ester.

[0014] The structure of the above monomer A is shown in equation (4):

[0015]

[0016] In this context, R1 is a hydrogen atom or a methyl group; R4 is a hydrogen atom or a group with 1-4 carbon atoms.

[0017] The monomer B mentioned above is vinylimidazole or 2'-propenylimidazole.

[0018] The structure of the above-mentioned large monomer P is shown in equation (5):

[0019]

[0020] Where R3 is a hydrogen atom or a methyl group, Y2 is a hydrocarbon group of C0 to C4, and the value of q ranges from 15 to 150.

[0021] The above-mentioned halocarboxylic acid esters are C1-C4 esters of monochloro / brominated C2-C3 carboxylic acids.

[0022] This amphoteric multifunctional water-reducing agent comprises the following randomly distributed structural units I, II, and III. The water-reducing agent is a polymer, and the polymer sequence is composed of these three types of structural units: I, II, and III.

[0023] Structural unit I is a (meth)acrylate residue, as shown in formula (1):

[0024]

[0025] Wherein, R1 is a hydrogen atom or a methyl group; R4 is a sodium, potassium, or a group having 1-4 carbon atoms;

[0026] Structural unit II is a carboxylic acid / phosphonic acid modified vinyl or propenyl imidazole residue, as shown in formula (2):

[0027]

[0028] Wherein, R2 is a hydrogen atom or a methyl group, Y1 is a C1 to C4 hydrocarbon group, and Z is a carboxyl group, a carboxylic acid ester group, or a bisphosphonic acid hydroxymethyl group;

[0029] Structural unit III consists of ether-type polyoxyethylene ether residues, as shown in formula (3):

[0030]

[0031] Where R3 is a hydrogen atom or a methyl group, Y2 is a hydrocarbon group of C0 to C4, and the value of q ranges from 15 to 150;

[0032] In each of the above structural units, m, n, and p satisfy the following conditions:

[0033] (m+n): p=(2.0~6.0):1, m:n=(1-9):1.

[0034] The weight-average molecular weight of the above-mentioned amphoteric multifunctional water-reducing agents is 5000-50000 g / mol.

[0035] A method for preparing an amphoteric multifunctional water-reducing agent includes the following steps: (1) Preparation of polymer intermediates: monomers A, B, and macromonomer P are subjected to free radical polymerization to obtain polymer intermediate I1; (2) Modification of polymer intermediates: polymer intermediate I1 is subjected to acylation reaction with halocarboxylic acid esters; then phosphorus trichloride is added for phosphonic modification, hydrolyzed and byproducts are removed, and dried to obtain polymer intermediate I2; (3) Post-treatment: polymer intermediate I2 is dissolved in water, alkali is added for hydrolysis, byproducts are removed under reduced pressure and water is added to obtain a water-reducing agent with a mass concentration of 30-50%.

[0036] In the free radical polymerization process of step (1) above, an initiator and a molecular weight regulator are added. The initiator is an azo initiator, preferably azobisisobutyronitrile or azoisoheptanenitrile, and its molar amount is 0.5% to 2.0% of the total molar amount of the monomers participating in the reaction. The molecular weight regulator is an organic compound containing a mercapto group, preferably mercaptopropionic acid or dodecyl mercaptoside, and its molar amount is 1.5% to 5.0% of the total molar amount of the monomers participating in the reaction. The free radical polymerization reaction temperature of step (1) above is 45 to 75°C, and the time is 0.5 to 3 hours. Step (1) above is carried out under inert gas conditions, preferably under nitrogen protection. In step (1), monomer A is added dropwise and is completed within 1.5 to 5 hours.

[0037] The acylation reaction temperature in step (2) is 50-75℃ and the time is 2.5-8h; phosphorus trichloride in step (2) is added within 1.5-4h; the phosphonate modification temperature in step (2) is 100-120℃ and the time is 8-24h; the mass of water used for hydrolysis in step (2) is 20%-35% of the total mass of the previous reactants.

[0038] In step (3) above, the alkali is an aqueous solution of sodium hydroxide or potassium hydroxide, and its amount is 0.33 to 1.0 times the total molar amount of monomer A and monomer B; the hydrolysis reaction temperature in step (3) is 45 to 75°C, and the time is 2 to 8 hours.

[0039] The specific operation of step (1) is as follows: take a certain amount of monomer B and macromonomer P and add them to the reactor and mix them evenly. Then add the initiator and molecular weight regulator, heat the temperature to 45-75 degrees, and then add monomer A dropwise to the reaction system at this temperature. The monomer is added in 1.5-5 hours. Then keep the temperature for 0.5-3 hours to obtain polymer intermediate I1.

[0040] Step (2) is as follows: Take a certain amount of polymer intermediate I1 and add it to a dry reactor equipped with a tail gas absorption device. Heat the reactor to 50-75 degrees Celsius. After the polymer melts, add a certain amount of halocarboxylic acid ester to the reactor within 15 min to 1 h. Then react at this temperature for 2.5-8 h. After the reaction is completed, wait for more than 0.5 h and then slowly add a certain amount of phosphorus trichloride to the reactor within 1.5-4 h. After the addition is completed, heat the reactor to 100-120 degrees Celsius and react for 8-24 h. Then, transfer the reactants to another reactor, add a certain amount of water to hydrolyze the intermediate and by-products, and vacuum (vacuum degree 0.9-0.99 atm) to fully remove and recover the generated hydrogen chloride and water to obtain polymer intermediate I2.

[0041] Step (3) is as follows: Take a certain amount of polymer intermediate I2, dissolve it in water to prepare a solution with a mass concentration of 30-50%, then add a certain amount of alkali to it, and hydrolyze it at 45-75 degrees for 2-8 hours; then, remove and recover the generated alcohol byproducts by fractionation under reduced pressure (vacuum degree 0.9-0.99 atmospheres); then replenish water to the reactor to a mass concentration of 30-50% to obtain the water-reducing agent.

[0042] When amphoteric multifunctional water-reducing agents are used in silicate cement-based cementitious systems, their dosage is 0.08% to 0.25% of the total mass of the cementitious materials. The water-reducing agent of this application has diverse, acid-base amphoteric adsorption groups, which have good adaptability to the increasingly diversified cementitious systems. It has obvious adaptability and performance advantages in new low-carbon cementitious systems such as high admixtures and LC3.

[0043] This application has the following advantages over the prior art:

[0044] (1) This application uses a "polymerization-modification" technical solution to avoid interference between functional groups and improve the controllability of molecular structure. The method of modification followed by polymerization will lead to problems such as reduced polymerization efficiency due to the influence of steric hindrance of functional groups between the modified monomers. By introducing imidazole groups into the main chain and modifying it with carboxylic acid and bisphosphonic acid, a multifunctional structure of conjugated cationic groups, carboxylic acid groups and bisphosphonic acid groups is formed. Through the synergistic effect of multifunctional groups, the conjugated cationic groups enhance charge adsorption, the carboxylic acid groups provide dispersion ability, the bisphosphonic acid groups improve anti-mud properties, and the highly reactive double bonds improve polymerization efficiency. The molecular weight distribution is more uniform, which significantly improves the adaptability and dispersion ability of the water-reducing agent to the new gelling system. The lack of any functional group structure will lead to a reduction in synergistic effect, and the dispersion and anti-mud properties will be significantly lower than those of the multifunctional synergistic water-reducing agent obtained by the "polymerization-modification" technical solution of this application.

[0045] (2) The water-reducing agent prepared in this application is suitable for high admixture concrete (such as mineral powder and fly ash system) and LC3 low carbon cementitious system, which can significantly improve workability, significantly reduce viscosity and improve construction efficiency. Detailed Implementation

[0046] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0047] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0048] The structural formulas of the main monomers used in the synthesis of each embodiment and comparative sample are shown in Table 1 below. After synthesis, the samples were characterized by a Shimazu LC-20AD gel permeation chromatograph with a mobile phase of 0.1 mol / L sodium nitrate and a flow rate of 1.0 mL / min.

[0049] Table 1

[0050]

[0051]

[0052] Example 1

[0053] Take 8.8 parts by mass of monomer B-1 and 350 parts by mass of macromonomer P-1 and add them to the reactor and mix them evenly. Then add 0.94 parts by mass of azobisisobutyronitrile and 1.67 parts by mass of mercaptopropionic acid. Heat the mixture to 60 degrees Celsius. Then add 24 parts by mass of monomer A-1 dropwise to the reaction system at this temperature. The monomers are added dropwise over 2.5 hours. Then keep the mixture at this temperature for another 1.5 hours to obtain polymer intermediate I1-1.

[0054] Take 300 parts by mass of polymer intermediate I1-1 and add it to a dry reactor equipped with a tail gas absorption device. Heat the reactor to 65 degrees Celsius. After the polymer melts, add 7.9 parts by mass of methyl chloroacetate to the reactor within 30 minutes. Then react at this temperature for 5 hours. After the reaction is complete, wait for more than 0.5 hours and then slowly add 15 parts by mass of phosphorus trichloride to the reactor within 2.5 hours. After the addition is complete, heat the reactor to 110 degrees Celsius and react for 12 hours. Then, transfer the reactants to another reactor and add 90 parts by mass of water to hydrolyze the intermediate and by-products. Vacuum the reactor to remove and recover the generated hydrogen chloride and water, and obtain polymer intermediate I2-1.

[0055] Take 250 parts by mass of polymer intermediate I2-1, dissolve it in water to prepare a solution with a mass concentration of 40%, then add 19.5 parts by mass of 35% liquid alkali, and hydrolyze at 60 degrees for 6 hours; then, remove and recover the generated alcohol byproducts by vacuum distillation; then add water back to the reactor to a mass concentration of 45%, to obtain water-reducing agent S-1 with a weight average molecular weight of 23410 g / mol and a yield of 85.30%.

[0056] Example 2

[0057] 4.7 parts by mass of monomer B-2 and 150 parts by mass of macromonomer P-2 were added to the reactor and mixed evenly. Then, 0.75 parts by mass of azobisisoheptanenitrile and 0.80 parts by mass of mercaptopropionic acid were added, and the temperature was raised to 50 degrees Celsius. Then, 30.3 parts by mass of monomer A-2 were added dropwise to the reaction system at this temperature. The monomers were added dropwise over 4 hours. After that, the temperature was maintained for another 2 hours to produce polymer intermediate I1-2.

[0058] 150 parts by mass of polymer intermediate I1-2 were added to a dry reactor equipped with a tail gas absorption device. The temperature was raised to 55 degrees Celsius. After the polymer melted, 3.4 parts by mass of ethyl chloroacetate were added to the reactor within 15 minutes. The reaction was then carried out at this temperature for 6 hours. After the reaction was completed, the reactor was allowed to wait for more than 0.5 hours. Then, 8.6 parts by mass of phosphorus trichloride were slowly added to the reactor within 2 hours. After the addition was completed, the temperature was raised to 105 degrees Celsius and the reaction was carried out for 22 hours. The reactants were then transferred to another reactor. 35 parts by mass of water were added to hydrolyze the intermediate and by-products. The generated hydrogen chloride and water were thoroughly removed and recovered under vacuum to obtain polymer intermediate I2-2.

[0059] Take 150 parts by mass of polymer intermediate I2-2, dissolve it in water to prepare a 50% by mass solution, then add 3.4 parts by mass of solid sodium hydroxide, and hydrolyze at 75 degrees for 2 hours; then, remove and recover the generated alcohol byproducts by vacuum distillation; then add water back to the reactor to a concentration of 50% by mass to obtain water-reducing agent S-2 with a weight average molecular weight of 7603 g / mol and a yield of 88.03%.

[0060] Example 3

[0061] Take 8.5 parts by mass of monomer B-3 and 450 parts by mass of macromonomer P-3 and add them to the reactor and mix them evenly. Then add 1.36 parts by mass of azobisisobutyronitrile and 2.79 parts by mass of dodecanethiol. Heat the mixture to 75 degrees Celsius. Then add 41.1 parts by mass of monomer A-3 dropwise to the reaction system at this temperature. The monomers are added dropwise over 2 hours. Then keep the mixture at this temperature for another hour to obtain polymer intermediate I1-3.

[0062] 400 parts by mass of polymer intermediate I1-3 were added to a dry reactor equipped with a tail gas absorption device. The temperature was raised to 65 degrees Celsius. After the polymer melted, 10.3 parts by mass of methyl bromoacetate were added to the reactor within 1 hour. The reaction was then carried out at this temperature for 2.5 hours. After the reaction was completed, the reactor was allowed to wait for more than 0.5 hours. Then, 11.8 parts by mass of phosphorus trichloride were slowly added to the reactor within 2.5 hours. After the addition was completed, the temperature was raised to 110 degrees Celsius and the reaction was carried out for 16 hours. The reactants were then transferred to another reactor. 145 parts by mass of water were added to hydrolyze the intermediate and by-products. The generated hydrogen chloride and water were thoroughly removed and recovered under vacuum to obtain polymer intermediate I2-3.

[0063] Take 350 parts by mass of polymer intermediate I2-3, dissolve it in water to prepare a solution with a mass concentration of 40%, then add 15 parts by mass of solid potassium hydroxide, and hydrolyze at 45 degrees for 6 hours; then, remove and recover the generated alcohol byproducts by vacuum distillation; then add water back to the reactor to a mass concentration of 40%, to obtain water-reducing agent S-3 with a weight average molecular weight of 31753 g / mol and a yield of 86.01%.

[0064] Example 4

[0065] 28.8 parts by mass of monomer B-4 and 600 parts by mass of macromonomer P-4 were added to the reactor and mixed evenly. Then, 2.14 parts by mass of azobisisobutyronitrile and 3.46 parts by mass of mercaptopropionic acid were added, and the temperature was raised to 70 degrees Celsius. Then, 25 parts by mass of monomer A-4 were added dropwise to the reaction system at this temperature. The monomers were added dropwise over 4 hours. Then, the temperature was maintained for another 2.5 hours to produce polymer intermediate I1-4.

[0066] 600 parts by mass of polymer intermediate I1-4 were added to a dry reactor equipped with a tail gas absorption device. The temperature was raised to 75 degrees Celsius. After the polymer melted, 44.5 parts by mass of methyl bromoacetate were added to the reactor within 30 minutes. The reaction was then carried out at this temperature for 7.5 hours. After the reaction was completed, the reactor was allowed to wait for more than 0.5 hours. Then, 38.3 parts by mass of phosphorus trichloride were slowly added to the reactor within 3.5 hours. After the addition was completed, the temperature was raised to 120 degrees Celsius and the reaction was carried out for 10 hours. The reactants were then transferred to another reactor. 220 parts by mass of water were added to hydrolyze the intermediate and by-products. The generated hydrogen chloride and water were thoroughly removed and recovered under vacuum to obtain polymer intermediate I2-4.

[0067] Take 500 parts by mass of polymer intermediate I2-4, dissolve it in water to prepare a 30% by mass solution, then add 43 parts by mass of 35% liquid alkali, and hydrolyze at 75 degrees for 6 hours; then, remove and recover the generated alcohol byproducts by vacuum distillation; then add water back to the reactor to a concentration of 30% by mass to obtain water-reducing agent S-4 with a weight average molecular weight of 46672 g / mol and a yield of 82.26%.

[0068] Example 5

[0069] Take 9.5 parts by mass of monomer B-5 and 250 parts by mass of macromonomer P-5 and add them to the reactor and mix them evenly. Then add 0.66 parts by mass of azobisisobutyronitrile and 1.70 parts by mass of mercaptopropionic acid. Heat the mixture to 45 degrees Celsius. Then add 23.9 parts by mass of monomer A-5 dropwise to the reaction system at this temperature. The monomers are added dropwise over 1.5 hours. Then keep the mixture at this temperature for another 0.5 hours to obtain polymer intermediate I1-5.

[0070] 250 parts by mass of polymer intermediate I1-5 were added to a dry reactor equipped with a tail gas absorption device. The temperature was raised to 55 degrees Celsius. After the polymer melted, 10.3 parts by mass of ethyl chloroacetate were added to the reactor within 20 minutes. The reaction was then carried out at this temperature for 4 hours. After the reaction was completed, the reactor was allowed to wait for more than 0.5 hours. Then, 19.5 parts by mass of phosphorus trichloride were slowly added to the reactor within 2 hours. After the addition was completed, the temperature was raised to 100 degrees Celsius and the reaction was carried out for 24 hours. The reactants were then transferred to another reactor. 80 parts by mass of water were added to hydrolyze the intermediate and by-products. The generated hydrogen chloride and water were thoroughly removed and recovered under vacuum to obtain polymer intermediate I2-5.

[0071] Take 200 parts by mass of polymer intermediate I2-5, dissolve it in water to prepare a solution with a mass concentration of 45%, then add 17.8 parts by mass of 35% liquid alkali, and hydrolyze at 60 degrees for 6 hours; then, remove and recover the generated alcohol byproducts by vacuum distillation; then add water back to the reactor to a mass concentration of 50%, to obtain water-reducing agent S-5 with a weight average molecular weight of 28873 g / mol and a yield of 83.90%.

[0072] Test Example 1:

[0073] The performance characteristics and benefits of the above embodiments were verified by testing their dispersion effect on cement mortar and concrete. In addition to the samples synthesized in each embodiment, PCA-VIII commercial polycarboxylate superplasticizer provided by Jiangsu Subote New Material Co., Ltd. was also used as a comparison.

[0074] The test material specifications and procedures are based on GB8076-2008 and GB50082-2009.

[0075] First, mortar tests were conducted to preliminarily evaluate the water-reducing effect of each embodiment. PI 42.5 reference cement was used in the tests, and the component analysis results of this cement are shown in Table 2 below. The component analysis was based on X-ray diffraction characterization - Rietveld method (Brook D8 Advance X-ray diffractometer, Cu Kα line).

[0076] Table 2 shows the cement mineral phase composition used.

[0077] Components C3S C2S C3A C4AF limestone plaster content 56.3 17.9 8.0 6.9 <0.1 5.3

[0078] The test used 650g of cement and 1350g of ISO standard sand, with a water-cement ratio of 0.35. The test results are shown in Table 3 below.

[0079] Table 3. Spreadability of modified mortar in the examples

[0080] sample Dosage 4min 15min 30min 60min S-1 0.135 278 260 232 215 S-2 0.135 257 237 225 210 S-3 0.135 283 271 243 217 S-4 0.135 269 245 229 206 S-5 0.135 276 268 253 231 PCA-VIII 0.135 226 210 193 PCA-VIII 0.150 270 257 231 202

[0081] As can be seen from the results in Table 3 above, the water-reducing agent prepared using the preparation method disclosed in this application has significantly better water-reducing performance in ordinary mortar than the PCA-VIII type commercial water-reducing agent used as a control.

[0082] Test Example 2:

[0083] The dispersion effect of the water-reducing agent in high-concrete-admixture concrete is shown in Table 4 below. The specific test results are shown in Table 5. The cement used is still the aforementioned PI 42.5 cement.

[0084] Table 4

[0085] cement Mineral powder fly ash water sand Xiaoshi Zhongshi Dashi 180 110 160 160 720 315 315 425

[0086] Table 5

[0087]

[0088] As can be seen from Table 5 above, each embodiment not only had a greater initial water reduction than the control group, but also a significantly faster collapse time, indicating that it overcame the high viscosity problem of the high admixture system, which is a significant advantage in construction.

[0089] Test Example 3:

[0090] The dispersion effect of the water-reducing agent in LC3 type cementitious concrete is shown in Table 6 below, and the specific test results are shown in Table 7. The cement used is still the aforementioned PI 42.5 cement.

[0091] Table 6

[0092] cement Calcinated clay limestone powder plaster water sand Xiaoshi Zhongshi Dashi 167.5 115 60 7.5 175 700 200 430 420

[0093] Table 7

[0094]

[0095] It can be seen that in LC3 concrete containing a large amount of calcined clay, the difference between the PCA-VIII and the example sample as a comparison is significantly widened. At the same time, the collapse time is still significantly longer, which shows the dispersion advantage of the example sample in the LC3 concrete system.

[0096] In summary, the water-reducing agent disclosed in this invention has excellent performance, which is better than the control commercial water-reducing agent. At the same time, it has good adaptability to high admixtures and novel cementitious systems such as LC3.

[0097] The technical solution of this application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention, including the best mode, and also to enable any person skilled in the art to practice this invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the wording of the claims, or if they include equivalent structural elements that are not substantially different from the wording of the claims, then these other embodiments should also be included within the scope of the claims. For those skilled in the art, it is understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of this invention, and the scope of this invention is defined by the appended claims and their equivalents.

Claims

1. An amphoteric multifunctional water-reducing agent, characterized in that, The product is obtained by polymerizing monomers A, B, and P, followed by acylation of the polymerization intermediate with a halocarboxylic acid ester, and then phosphonation modification by introducing phosphorus trichloride. The monomer A is an acrylate; The monomer B is an alkenyl imidazolium class; The macromonomer P is an ether-type polyoxyethylene ether macromonomer containing double bond end groups, whose segment units are composed of ethylene oxide residues, and the total number of segment units is between 15 and 150. The molar ratio of monomer A, monomer B, and macromonomer P is (n A +n B ):n P =(2.0~6.0):1, n A :n B =(1-9):1; The molar amount of the halocarboxylic acid ester is 0.8 to 1.05 times the molar amount of the imidazole group in the polymer intermediate; the molar amount of phosphorus trichloride is 0.6 to 1.8 times the molar amount of the imidazole group in the polymer intermediate, and not more than twice the molar amount of the halocarboxylic acid ester. The amphoteric multifunctional water-reducing agent has a weight-average molecular weight of 5000–50000 g / mol.

2. The amphoteric multifunctional water-reducing agent according to claim 1, characterized in that, The structure of monomer A is shown in equation (4) below: In this context, R1 is a hydrogen atom or a methyl group; R4 is a hydrogen atom or a group with 1-4 carbon atoms.

3. The amphoteric multifunctional water-reducing agent according to claim 1, characterized in that: The monomer B is vinylimidazole or 2'-propenylimidazole.

4. The amphoteric multifunctional water-reducing agent according to claim 1, characterized in that, The structure of the large monomer P is shown in equation (5): Where R3 is a hydrogen atom or a methyl group, Y2 is a hydrocarbon group of C0 to C4, and the value of q ranges from 15 to 150.

5. The amphoteric multifunctional water-reducing agent according to claim 1, characterized in that: The halocarboxylic acid ester is a C1-C4 ester of a monochloro / brominated C2-C3 carboxylic acid.

6. The amphoteric multifunctional water-reducing agent according to claim 1, characterized in that, This amphoteric multifunctional water-reducing agent contains the following randomly distributed structural units I, II, and III: Structural unit I is shown in equation (1): Wherein, R1 is a hydrogen atom or a methyl group; R4 is a sodium, potassium, or a group having 1-4 carbon atoms; Structural unit II is shown in equation (2): Wherein, R2 is a hydrogen atom or a methyl group, Y1 is a C1 to C4 hydrocarbon group, and Z is a carboxyl group, a carboxylic acid ester group, or a bisphosphonic acid hydroxymethyl group; Structural unit III is shown in equation (3): Where R3 is a hydrogen atom or a methyl group, Y2 is a hydrocarbon group of C0 to C4, and the value of q ranges from 15 to 150; In each structural unit, m, n, and p satisfy the following conditions: (m+n): p=(2.0~6.0):1, m:n=(1-9):

1.

7. A method for preparing an amphoteric multifunctional water-reducing agent according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of polymer intermediates: Monomer A, monomer B and macromonomer P were subjected to free radical polymerization to obtain polymer intermediate I1; (2) Modification of polymer intermediates: Polymer intermediate I1 is acylated with halocarboxylic acid ester; then phosphorus trichloride is added for phosphonic modification, hydrolyzed and by-products are removed, and dried to obtain polymer intermediate I2; (3) Post-treatment: Polymer intermediate I2 is dissolved in water, alkali is added for hydrolysis, by-products are removed under reduced pressure and water is added to obtain a water-reducing agent with a mass concentration of 30-50%.

8. The preparation method according to claim 7, characterized in that: In step (1), an initiator and a molecular weight regulator are added to the free radical polymerization reaction. The initiator is an azo initiator, and its molar amount is 0.5% to 2.0% of the total molar amount of the monomers participating in the reaction. The molecular weight regulator is an organic compound containing a thiol group, and its molar amount is 1.5% to 5.0% of the total molar amount of the monomers participating in the reaction. The free radical polymerization reaction temperature in step (1) is 45 to 75°C, and the time is 0.5 to 3 hours. Step (1) is carried out under inert gas conditions. In step (1), monomer A is added dropwise and the addition is completed within 1.5 to 5 hours.

9. The preparation method according to claim 7, characterized in that: The acylation reaction temperature in step (2) is 50-75℃, and the time is 2.5-8h; phosphorus trichloride in step (2) is added within 1.5-4h; the phosphonate modification temperature in step (2) is 100-120℃, and the time is 8-24h; the mass of water used for hydrolysis in step (2) is 20%-35% of the total mass of the previous reactants.

10. The preparation method according to claim 7, characterized in that: In step (3), the alkali is an aqueous solution of sodium hydroxide or potassium hydroxide, and its amount is 0.33 to 1.0 times the total molar amount of monomer A and monomer B. The hydrolysis reaction in step (3) is carried out at a temperature of 45–75°C for 2–8 hours.

11. The application of an amphoteric multifunctional water-reducing agent in silicate cement-based cementitious systems, characterized in that: The water-reducing agent is added at a rate of 0.08% to 0.25% of the total mass of the cementitious material; the amphoteric multifunctional water-reducing agent is an amphoteric multifunctional water-reducing agent as described in any one of claims 1-6 or an amphoteric multifunctional water-reducing agent prepared by the preparation method described in any one of claims 7-10.

Images