Heterocycle-containing amphoteric phosphoric acid monomer, preparation method thereof and phosphate water reducer prepared based on heterocycle-containing amphoteric phosphoric acid monomer

Abstract

The invention discloses a heterocycle-containing amphoteric phosphoric acid monomer, a preparation method thereof and a phosphate water reducer prepared based on the heterocycle-containing amphoteric phosphoric acid monomer. The phosphate-based water reducer is prepared by the following steps: carrying out free radical copolymerization reaction on a carboxylic acid monomer, an amphoteric phosphate monomer containing heterocyclic rings and a polyether macromonomer under the action of an initiator and a chain transfer agent to obtain a polymer, neutralizing with liquid caustic soda, and diluting with water, the preparation method of the amphoteric phosphoric acid monomer containing the heterocyclic ring comprises the following steps: firstly, carrying out quaternization reaction on a nitrogen heterocyclic compound containing a double bond and epoxy chloropropane to obtain quaternary ammonium salt, then carrying out ion exchange reaction on the quaternary ammonium salt and anion exchange resin to obtain a compound A, and finally adding phosphoric acid into the compound A to obtain the amphoteric phosphoric acid monomer containing the heterocyclic ring. The prepared water reducing agent is applied to concrete containing machine-made sand, has the effects of adsorbing and providing large steric hindrance, and can promote hydration of cement and accelerate development of early strength of the concrete while maintaining good workability of the concrete.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete admixtures, and particularly relates to an amphoteric phosphoric acid monomer containing a heterocyclic ring, a preparation method thereof and a phosphoric acid-based water reducing agent prepared based on the same. BACKGROUND

[0002] In recent years, with the increase in the use and mining of natural sand in concrete, the environment of rivers and lakes is damaged, and the state has gradually promulgated regulations to limit the overuse of natural sand. Under this background, the use of artificial machine-made sand will gradually replace natural sand and become a development trend. However, the machine-made sand has a high content of mud and powder, and the size and particle size distribution of the machine-made sand are not the same. The commonly used polycarboxylate superplasticizer usually has poor adaptability in concrete containing machine-made sand, has a high usage amount, has a large slump loss over time, and seriously affects the workability and mechanical strength of the concrete. There is a lack of high-quality admixtures matching machine-made sand in the market, which directly limits the use and promotion of machine-made sand in concrete prefabricated components.

[0003] Patent CN107868243B discloses a preparation method of an amino acid derivative phosphorous acid water reducing agent. At present, the adaptability of the water reducing agent and clay is poor, and the prepared water reducing agent has excellent retarding effect and slump retention performance. However, the amino acid used in the patent may not be suitable for mass production and industrial production from the perspectives of raw material cost and product purity. Patent CN117683226B reports a phosphonic acid group-containing quaternary ammonium salt type water reducing agent. The presence of the phosphonic acid group and the quaternary ammonium salt makes the water reducing agent have excellent viscosity reduction and workability enhancement effects. The patent uses hypochlorous acid in the reaction. The substance has strong oxidizing property and is easy to have oxidation-reduction reaction with other substances to generate substances containing chlorine elements, which is not conducive to the use of the water reducing agent in concrete, especially in major engineering projects. Patent CN114292367B discloses an anti-mud water-retaining polycarboxylate superplasticizer for machine-made sand concrete. The unsaturated ester monomer is synthesized and introduced into the polycarboxylate superplasticizer together with the crosslinking anti-mud monomer to have the anti-mud water-retaining performance. However, the preparation process is carried out in a microwave reactor, which is not conducive to the industrialization of the product. Moreover, the product concrete test content only has the initial state characteristics and no more test data such as mechanical properties. The use environment content of the machine-made sand is not disclosed in detail. In addition, the different lithology, different gradation, different stone powder content and different mud content of the machine-made sand will bring the problems of poor adaptability, high dosage, high viscosity, difficult dispersion and easy bleeding of the water reducing agent and the concrete.

[0004] There are few water reducing agents suitable for machine-made sand in the prior art. From the perspectives of technical effect and economic benefit, the water reducing agent prepared from the new phosphoric acid monomer has great use prospect and market potential. SUMMARY

[0005] In view of the problems in the prior art, the present application designs and prepares an amphoteric phosphonic monomer containing a heterocycle, which is used to prepare a phosphonic-based water reducing agent for concrete containing machine-made sand. The phosphonic monomer in the present application contains both a polybasic phosphonic group and a quaternary ammonium salt cation, and when the water reducing agent prepared therefrom is applied to concrete containing machine-made sand, it has both adsorption and large steric hindrance effects, can maintain good and easy workability of the concrete, and can promote cement hydration and accelerate the development of early strength of the concrete. Moreover, the prepared water reducing agent greatly eliminates the negative effects of halogens by strictly controlling the use of anion exchange resin, and the reactions are highly efficient and mature, and most of them have been or can be industrialized.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] An amphoteric phosphonic monomer containing a heterocycle, the general structure of which is shown in formula (I) or (II):

[0008]

[0009] wherein Y1 and Y2 are alkenes with a carbon atom number of not more than 4 and their substitutes; the position of Y1 on the pyridine heterocycle is any substitution position except the position of the N atom; R1 is an alkyl substituent with a carbon atom number of not more than 4, and the position of R1 on the heterocycle is any position except the positions of Y1 and the N atom; the position of Y2 on the imidazole heterocycle is the 1-, 2-, 3-, 4- or 5-substitution position, R2 is an alkyl substituent with a carbon atom number of not more than 4, and the position of R2 on the heterocycle is any position except the position of Y2, and Y2 and R2 cannot be on two N atoms at the same time; X is a divalent anion that is non-halogen and stable in chemical properties.

[0010] Further, the present application also provides a preparation method of the above-mentioned amphoteric phosphonic monomer containing a heterocycle, comprising the following steps:

[0011] (1) quaternary ammonium salt containing both a double bond and an epoxy group is obtained by quaternary ammonium reaction of a nitrogen heterocyclic compound containing a double bond with epichlorohydrin;

[0012] (2) ion exchange reaction of the quaternary ammonium salt obtained in step (1) with anion exchange resin is carried out, and the chlorine ion in the quaternary ammonium salt is replaced by a non-halogen ion through the ion exchange reaction to obtain compound A;

[0013] the non-halogen ion is a sulfate ion;

[0014] (3) phosphoric acid is added to the compound A obtained in step (2) to carry out ring-opening reaction of the epoxy group in the compound A with the phosphoric acid, and the novel amphoteric phosphonic monomer containing a heterocycle is obtained.

[0015] The double-bond-containing nitrogen heterocyclic compound in step (1) is an unsaturated pyridine compound or an unsaturated imidazole compound, wherein the unsaturated pyridine compound has a general structure of formula (III) and the unsaturated imidazole compound has a general structure of formula (IV):

[0016]

[0017] The molar ratio of the double-bond-containing nitrogen heterocyclic compound to epichlorohydrin in step (1) is 1:1.02-1.20.

[0018] The molar ratio of the anion in the anion exchange resin to the halogen ion in the quaternary ammonium salt in step (2) is 10-50:1.

[0019] The molar ratio of the phosphoric acid to the epoxy group in compound A in step (3) is 1.01-1.50:1.

[0020] Further, the specific preparation method of step (1) of the present application comprises: placing the double-bond-containing nitrogen heterocyclic compound and epichlorohydrin in a solvent to undergo a quaternary ammonium reaction, thereby obtaining a quaternary ammonium salt containing both a double bond and an epoxy group.

[0021] The solvent is a low-boiling-point solvent, and the amount of the solvent is 1-2 times the mass of the reactants, i.e., the reaction system is a solution with a mass concentration of 30-50%, and the solvent is preferably any one of methanol, ethanol, ethyl acetate, acetone, and acetonitrile.

[0022] The quaternary ammonium reaction is a reflux reaction at 60-80°C under normal pressure, and the reaction time is 8-24 h.

[0023] After the quaternary ammonium reaction is completed, the solvent and excess epichlorohydrin are removed by reduced-pressure distillation and vacuum drying, thereby obtaining the quaternary ammonium salt containing both a double bond and an epoxy group.

[0024] Further, the unsaturated pyridine compound in step (1) of the present application is selected from any one of 2-vinylpyridine, 3-vinylpyridine, and 4-vinylpyridine.

[0025] Further, the unsaturated imidazole compound in step (1) of the present application is selected from any one of 1-vinylimidazole, 2-vinylimidazole, 3-vinylimidazole, 4-vinylimidazole, and 5-vinylimidazole.

[0026] Further, the ion exchange reaction in step (2) of the present application is performed in methanol, and the ion exchange reaction time is 8-12 h, and the ion exchange reaction is performed at room temperature; after the ion exchange reaction is completed, the anion exchange resin is removed by filtration, and then methanol is removed by reduced-pressure distillation and vacuum drying, thereby obtaining compound A.

[0027] Further, the specific preparation method of step (3) comprises: dissolving compound A obtained in step (2) and phosphoric acid in acetone respectively to form a homogeneous solution, then adding the phosphoric acid solution into the compound A solution, and using the phosphoric acid to open the ring of the epoxy group in the compound A to obtain the novel heterocyclic-containing amphoteric phosphoric acid monomer.

[0028] The concentration of the reaction system is controlled at 30-50 wt%;

[0029] The reaction temperature is -10-10℃;

[0030] The dropping time is 2-2.5h, and the normal dropping time is 2h; if the reaction is exothermic, the dropping speed needs to be reduced, and the dropping time is extended to 2.5h; after the dropping is completed, the reaction is continued for 2h, and then acetone and water are removed by vacuum distillation and vacuum drying to obtain the heterocyclic-containing amphoteric phosphoric acid monomer.

[0031] Further, the application further provides a phosphoric acid-based water reducing agent based on the above-mentioned heterocyclic-containing amphoteric phosphoric acid monomer, which is obtained by free radical copolymerization of a carboxylic acid monomer, the above-mentioned heterocyclic-containing amphoteric phosphoric acid monomer, and a polyether macromonomer under the action of an initiator and a chain transfer agent, and then by neutralization with liquid alkali and dilution with water.

[0032] The molar ratio of the polyether macromonomer, the heterocyclic-containing amphoteric phosphoric acid monomer, and the carboxylic acid monomer is 1:(1-4):(1-3);

[0033] The initiator is a redox initiator.

[0034] Further, the carboxylic acid monomer in the application is selected from any one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride, and sodium or potassium salt thereof.

[0035] Further, the weight average molecular weight of the polyether macromonomer in the application is 1000-5000, and is specifically selected from any one of allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, methylallyl polyoxyethylene ether, and ethylene glycol monovinyl polyethylene glycol ether.

[0036] Further, the chain transfer agent in the application is selected from any one of mercaptoethanol, mercaptoacetic acid, mercapto propanol, and mercapto propionic acid, and the amount of the chain transfer agent is 0.5-5% of the total moles of the reaction monomers.

[0037] Further, the application further provides a preparation method of the above-mentioned phosphoric acid-based water reducing agent, which comprises the following steps:

[0038] (1) preparing a base material: adding a polyether macromonomer and water into a reactor, stirring at room temperature until complete dissolution, and obtaining a base material;

[0039] (2) Preparation of dropping solution I: the reducing agent and chain transfer agent are added into water, and stirred uniformly to obtain dropping solution I;

[0040] (3) Preparation of dropping solution II: the carboxylic acid monomer and the amphoteric phosphoric acid monomer containing heterocycle are added into water, and stirred uniformly to obtain dropping solution II;

[0041] (4) The oxidizing agent is added into the base material, and stirred for 2-10 min; dropping solution I and dropping solution II are sequentially added into the reactor at 40-80 DEG C; after the dropping is completed, the heat preservation reaction is continuously carried out;

[0042] (5) After the reaction is completed, the alkaline solution is used for neutralization until the pH value is 5.0-7.0, and water is used for dilution until the mass fraction is 30-50%, so that the phosphoric acid group water reducing agent is obtained.

[0043] The mass concentration of the polyether macromonomer in the base material in step (1) is 60%, if it is a solid polyether, the 60% aqueous solution is prepared according to the actual need, and then used.

[0044] The reducing agent in step (2) is selected from any one of L-ascorbic acid, sodium sulfite, sodium bisulfite and chalk powder, and the amount of the reducing agent is 0.5-3% of the total molar amount of the reaction monomers; the mass concentration of the dropping solution I is 50%.

[0045] The mass concentration of the dropping solution II in step (3) is 50%.

[0046] The oxidizing agent in step (4) is selected from any one of hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate, and the amount of the oxidizing agent is 2-6% of the total molar amount of the reaction monomers; the dropping time of the dropping solution II is 2-5 h, the dropping time of the dropping solution I is 2.5-6 h, and the dropping time of the dropping solution I is at least 0.5 h longer than that of the dropping solution II; the heat preservation reaction time is at least 1 h.

[0047] The mass fraction of the alkaline solution in step (5) is 50%, and the alkaline solution is an aqueous solution of monovalent or divalent metal hydroxide.

[0048] Compared with the prior art, the present application has the following beneficial effects:

[0049] (1) The water reducing agent prepared in the present application is an amphoteric polyelectrolyte, and has a counter polyelectrolyte effect; under the condition of strong electrolyte and strong alkali, the molecular structure will not curl, but will be more expanded, which is beneficial to the adsorption of the special functional groups in the water reducing agent on the cement particles, and the dispersion effect is better and the water reducing rate is higher under the action of the double adsorption groups of carboxylic acid and phosphoric acid groups.

[0050] (2) The new amphoteric phosphoric monomer in the application can improve the limitation that the existing water reducing agent molecules can only act on positively charged particles, can improve the effective adsorption amount, is particularly suitable for an environment system containing different mechanism sands, has good adaptability in different cements, and is expected to promote the global application of mechanism sand in different strength grade concretes.

[0051] (3) The water reducing agent molecule prepared in the application has a large steric structure of nitrogen heterocycle and double phosphoric groups, has low dosage and low sensitivity compared with conventional polycarboxylic acid water reducing agents, can promote the early hydration of cement by introducing appropriate cations, significantly improves the early strength, promotes the hydration process of cement, and can improve the early strength of concrete. DETAILED DESCRIPTION

[0052] The technical solutions of the application will be described clearly and completely in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0053] The weight average molecular weight of the polymer in the application is determined by using a gel permeation chromatograph (gel column: Shodex SB806+803 chromatographic column in series; eluent: 0.1M NaNO3 aqueous solution; flow rate: 0.8mL / min; injection: 20μL of 0.5% aqueous solution; detector: Shodex RI-71 type differential refractive index detector; standard substance: polyethylene glycol GPC standard (Sigma-Aldrich molecular weight 1010000, 478000, 263000, 118000, 44700, 18600, 6690, 1960, 628, 232).

[0054] (I) Preparation of amphoteric phosphoric monomer containing heterocycle

[0055] Preparation Example 1

[0056] A preparation method of an amphoteric phosphoric monomer of a heterocycle comprises:

[0057] (1) 2-vinylpyridine (1 mol) and epichlorohydrin (1.05 mol) are dissolved in ethyl acetate, and reacted at 70℃ under reflux conditions for 8h. After the reaction is completed, ethyl acetate and epichlorohydrin are removed to obtain a quaternary ammonium salt containing double bonds and epoxy groups;

[0058] (2) The quaternary ammonium salt (1 mol) is dissolved in methanol, 30 mol of a sulfate ion exchange resin is added, and after ion exchange reaction for 8h, the ion exchange resin is removed by filtration, and then methanol is removed by vacuum distillation and vacuum drying to obtain compound A;

[0059] (3) Dissolve 1 mol of Compound A and 1.1 mol of phosphoric acid in acetone to make a 50% solution, under the condition of 0°C, add dropwise the acetone solution of Compound A, the dropwise adding time is 2 h; after the dropwise adding, continue to react for 2 h under the same temperature; after the reaction, remove the acetone and water by distillation under reduced pressure and vacuum drying to obtain the amphoteric phosphoric acid monomer containing pyridine heterocycle, which is noted as PM-1.

[0060] Similarly, use 3-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, 2-vinylimidazole, 4-vinylimidazole respectively in Examples 2-6, after reacting with epichlorohydrin, then ion exchange reaction, and finally react with phosphoric acid to obtain the amphoteric phosphoric acid monomer containing heterocycle.

[0061] Preparation Example 2

[0062] Different from Preparation Example 1, use 1 mol of 3-vinylpyridine, 1.06 mol of epichlorohydrin (ethanol as solvent, 60°C, 10 h), ion exchange resin (35 eq. based on the molar number of chloride ion in quaternary ammonium salt; ion exchange reaction time 10 h), phosphoric acid (1.15 eq. based on the molar number of actually obtained Compound A; dropwise adding for 2 h at -5°C, after the dropwise adding, react for 2 h), to obtain the amphoteric phosphoric acid monomer containing pyridine heterocycle, which is noted as PM-2.

[0063] Preparation Example 3

[0064] Different from Preparation Example 1, use 1 mol of 4-vinylpyridine, 1.03 mol of epichlorohydrin (ethyl acetate as solvent, 70°C, 12 h), ion exchange resin (36 eq. based on the molar number of chloride ion in quaternary ammonium salt; ion exchange reaction time 10 h), phosphoric acid (1.18 eq. based on the molar number of actually obtained Compound 1; dropwise adding for 2.5 h at -10°C, after the dropwise adding, react for 2 h), to obtain the amphoteric phosphoric acid monomer containing pyridine heterocycle, which is noted as PM-3.

[0065] Preparation Example 4

[0066] Different from Preparation Example 1, use 1 mol of 1-vinylimidazole, 1.10 mol of epichlorohydrin (acetonitrile as solvent, 70°C, 18 h), ion exchange resin (32 eq. based on the molar number of chloride ion in quaternary ammonium salt; ion exchange reaction time 12 h), phosphoric acid (1.32 eq. based on the molar number of actually obtained Compound 1; dropwise adding for 2.5 h at -10°C, after the dropwise adding, react for 2 h), to obtain the amphoteric phosphoric acid monomer containing imidazole heterocycle, which is noted as PM-4.

[0067] Preparation Example 5

[0068] Instead of the preparation example 1, 1 mol of 2-vinylimidazole, 1.15 mol of epichlorohydrin (ethyl acetate as solvent, 80°C, 10 h), ion exchange resin (36 eq. based on the number of moles of chloride ion in the quaternary ammonium salt; ion exchange reaction time 10 h), phosphoric acid (1.35 eq. based on the number of moles of actually obtained compound 1; dropwise addition at -8°C for 2 h, and reaction for 2 h after the end of dropwise addition) were used to obtain a phosphoric acid-based amphiprotic monomer having a pyridine heterocycle, which is designated as PM-5.

[0069] Preparation Example 6

[0070] Instead of the preparation example 1, 1 mol of 4-vinylimidazole, 1.18 mol of epichlorohydrin (ethyl acetate as solvent, 60°C, 18 h), ion exchange resin (43 eq. based on the number of moles of chloride ion in the quaternary ammonium salt; ion exchange reaction time 12 h), phosphoric acid (1.4 eq. based on the number of moles of actually obtained compound 1; dropwise addition at 5°C for 2.5 h, and reaction for 2 h after the end of dropwise addition) were used to obtain a phosphoric acid-based amphiprotic monomer having a pyridine heterocycle, which is designated as PM-6.

[0071] (II) Preparation of the phosphoric acid-based water reducing agent

[0072] A method for preparing the above phosphoric acid-based water reducing agent, comprising the following steps:

[0073] (1) Preparation of a base material: polyether macromonomer and water are added to a reactor, and stirred at room temperature until completely dissolved to obtain a base material having a mass concentration of 60%;

[0074] (2) Preparation of a dropwise addition solution I: a reducing agent and a chain transfer agent are added to water, and stirred to obtain a dropwise addition solution I having a mass concentration of 50%;

[0075] The reducing agent is selected from any one of L-ascorbic acid, sodium sulfite, sodium bisulfite, and whiting, and the amount of the reducing agent is 0.5 to 3% of the total moles of the reaction monomers;

[0076] The chain transfer agent is selected from any one of mercaptoethanol, mercaptoacetic acid, mercapto-propanol, and mercapto-propanoic acid, and the amount of the chain transfer agent is 0.5 to 5% of the total moles of the reaction monomers;

[0077] (3) Preparation of a dropwise addition solution II: a carboxylic acid monomer and a phosphoric acid-based amphiprotic monomer having a heterocycle are added to water, and stirred to obtain a dropwise addition solution II having a mass concentration of 50%;

[0078] (4) An oxidizing agent is added to the base material, and stirred for 5 min, and then the dropwise addition solution I and the dropwise addition solution II are sequentially added to the reactor at 40 to 80°C, and after the completion of the dropwise addition, the reaction is continued for a certain time;

[0079] The oxidizing agent is selected from any one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, and the amount of the oxidizing agent is 2-6% of the total monomer molar amount; the dropping time of the dropping liquid II is 2-5h, the dropping time of the dropping liquid I is 2.5-6h, and the dropping time of the dropping liquid I is at least 0.5h longer than that of the dropping liquid II; and the reaction time is at least 1h;

[0080] (5) After the reaction is completed, the obtained product is neutralized to pH 5.0-7.0 with an alkaline solution with a mass fraction of 50%, and then diluted with water to a mass fraction of 50%, thereby obtaining the phosphoric acid-based water reducing agent;

[0081] The alkaline solution is an aqueous solution of hydroxide of a univalent or divalent metal.

[0082] The phosphoric acid-based water reducing agents of Examples 1-9 and Comparative Examples PCE-1 and 2 are prepared according to the above procedure, and the specific material proportions and preparation process parameters are shown in Table 1 and Table 2. Comparative Example PCE-4 is CSP-10 polycarboxylic acid high-performance water reducing agent from Guangdong Hongqiang New Materials Co., Ltd. Table 3 shows the GPC test information of the water reducing agents of the examples and comparative examples.

[0083] Table 1 Material proportions of the water reducing agents of the examples and comparative examples

[0084]

[0085]

[0086] Table 2 Reaction parameters for preparing the phosphoric acid-based water reducing agents

[0087]

[0088] Table 3 GPC test information of the water reducing agents of the examples and comparative examples

[0089] Sample name Conversion rate / % Mw / Da PDI HSP-1 92.12 24544 1.16 HSP-2 92.32 25853 1.18 HSP-3 91.98 26855 1.15 HSP-4 92.21 25467 1.14 HSP-5 92.11 26745 1.16 HSP-6 91.89 27131 1.13 HSP-7 91.78 25596 1.18 HSP-8 92.15 26452 1.16 HSP-9 92.12 26352 1.14 PCE-1 92.19 26526 1.16 PCE-2 93.01 25735 1.15 PCE-3 91.87 29865 1.16 PCE-4 92.24 23523 1.19

[0090] Application Examples

[0091] Application Example 1

[0092] Cement mortar fluidity test

[0093] The cement mortar fluidity test is performed according to the method for determining the fluidity of cement mortar in GB / T 2419-2005. The water reducing agents prepared are tested for mortar fluidity: cement 700g, machine-made sand (fineness modulus 2.9) 1350g, water-cement ratio w / c 0.40, and the dosage of the water reducing agent is 0.13-0.23% (based on the mass of cement). The results are shown in the following table.

[0094] Table 4 Mortar fluidity of the water reducing agents of the examples and comparative examples in different cements

[0095]

[0096]

[0097] From the mortar fluidity test of Table 4 above, it can be seen that the water reducing agent samples HSP-1 to 9 provided by the application can exhibit excellent dispersibility and slump retention under the condition of containing machine-made sand; although different time change characteristics are exhibited in Taicai cement, Helin cement and Haibo cement, the overall performance is better than that of the comparative sample: when the same initial fluidity is reached, the dosage of the comparative sample is significantly increased, and part of the samples basically lose fluidity after 30 min. Overall comparison, the samples of the application exhibit better dispersibility, slump retention and adaptability when containing machine-made sand, and the use dosage is lower than that of the comparative sample.

[0098] Application Example 2

[0099] The water reducing agent of each example and comparative example is applied to machine-made sand concrete, the concrete mixing ratio is shown in Table 5, three kinds of machine-made sand in Table 6 are selected, and the performance test results of the water reducing agent of each example and comparative example in different machine-made sand concrete are shown in Tables 7 to 9.

[0100] Table 5: Raw material ratio of concrete

[0101] Cement Mineral powder Fly ash Stone powder Machine-made sand Large stone Medium stone Small stone Water Water-binder ratio 4.14 1.08 1.26 0.99 13.32 10.53 5.49 3.69 3.0 0.46

[0102] Table 6: Description of machine-made sand

[0103] Machine-made sand variety Machine-made sand 1 Machine-made sand 2 Machine-made sand 3 Fineness modulus 2.5 3.0 3.5

[0104] Table 7: Test of water reducing agent in machine-made sand 1 containing concrete

[0105]

[0106] Table 8: Test of water reducing agent in machine-made sand 2 containing concrete

[0107]

[0108] Table 9: Test of water reducing agent in machine-made sand 3 containing concrete

[0109]

[0110]

[0111] As can be seen from Tables 7-9, the water-reducing agent provided by the application shows good dispersion and water-reducing effect in the machine-made sand with different fineness modulus, which can indicate that the water-reducing agent has good adaptability to the machine-made sand; the 1h slump / extension loss of the three groups of comparative samples and the commercially available polycarboxylic acid water-reducing agent is large, while the loss of the examples is small, which indicates that the slump retention of the sample of the examples is good. At the same time, the 1d, 3d, 7d and 28d compressive strength data of the comparative concrete can obviously show that the strength of HSP-1 to HSP-9 is obviously higher than that of the four groups of comparative samples, which indicates that the water-reducing agent can improve the early strength of the concrete, and the later strength is also improved to a certain extent. In combination, the water-reducing agent prepared by the application shows excellent workability in different machine-made sands, does not segregate and bleed, and the slurry wrapping property is also very good.

[0112] The above describes the preferred embodiments of the application in detail, but is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the application, and all fall within the protection scope of the application.

Claims

1. A heterocyclic amphoteric phosphate monomer, characterized in that, Its general structural formula is shown in formula (I) or (II): Wherein, Y1 and Y2 are alkenes and their substituents with no more than 4 carbon atoms; Y1 is located at any substitution position on the pyridine heterocycle except where the N atom is located; R1 is an alkyl substituent with no more than 4 carbon atoms, and R1 is located at any position on the heterocycle except where Y1 and the N atom are located; Y2 is located at a 1, 2, 3, 4 or 5-substituent position on the imidazole heterocycle; R2 is an alkyl substituent with no more than 4 carbon atoms, and R2 is located at any position on the heterocycle except where Y2 is located, and Y2 and R2 cannot be on two N atoms simultaneously; X is a non-halogenated and chemically stable divalent anion.

2. A method for preparing the heterocyclic amphoteric phosphate monomer according to claim 1, characterized in that, Includes the following steps: (1) Quaternization reaction of nitrogen heterocyclic compounds containing double bonds with epichlorohydrin is used to obtain quaternary ammonium salts containing both double bonds and epoxy groups. (2) The quaternary ammonium salt obtained in step (1) undergoes an ion exchange reaction with an anion exchange resin to replace the chloride ions in the quaternary ammonium salt with non-halogen ions, thereby obtaining compound A. (3) Add phosphoric acid to compound A obtained in step (2) and use phosphoric acid to carry out a ring-opening reaction on the epoxy group in compound A to obtain the heterocyclic amphoteric phosphoric acid monomer. The nitrogen heterocyclic compound containing a double bond mentioned in step (1) is an unsaturated pyridine compound or an unsaturated imidazole compound, wherein the general structural formula of the unsaturated pyridine compound is formula (III) and the general structural formula of the unsaturated imidazole compound is formula (IV):

3. The method for preparing the heterocyclic amphoteric phosphate monomer according to claim 2, characterized in that, The molar ratio of the double-bonded nitrogen heterocyclic compound to epichlorohydrin in step (1) is 1:1.02 to 1.20; The non-halogen ion mentioned in step (2) is sulfate ion, and the molar ratio of anion in the anion exchange resin to halide ion in the quaternary ammonium salt is 10 to 50:

1. The molar ratio of phosphoric acid to the epoxy group in compound A in step (3) is 1.01 to 1.50:

1.

4. The method for preparing the heterocyclic amphoteric phosphate monomer according to claim 2, characterized in that, The specific preparation method of step (1) includes: placing a nitrogen heterocyclic compound containing a double bond with epichlorohydrin in a solvent to undergo a quaternization reaction to obtain a quaternary ammonium salt containing both a double bond and an epoxy group; The solvent is a low-boiling-point solvent, and its amount is 1 to 2 times the mass of the reactants. The reaction system is a solution with a mass concentration of 30 to 50%. The solvent is preferably any one of methanol, ethanol, ethyl acetate, acetone, and acetonitrile. The quaternization reaction is a reflux reaction at 60-80°C under normal pressure for 8-24 hours. After the quaternization reaction is completed, the solvent and excess epichlorohydrin are removed by vacuum distillation and vacuum drying to obtain a quaternary ammonium salt containing double bonds and epoxy groups.

5. The method for preparing the heterocyclic amphoteric phosphate monomer according to claim 2, characterized in that, The unsaturated pyridine compound mentioned in step (1) is selected from any one of 2-vinylpyridine, 3-vinylpyridine, and 4-vinylpyridine; The unsaturated imidazole compound mentioned in step (1) is selected from any one of 1-vinylimidazole, 2-vinylimidazole, 3-vinylimidazole, 4-vinylimidazole, and 5-vinylimidazole.

6. The method for preparing the heterocyclic amphoteric phosphate monomer according to claim 2, characterized in that, The ion exchange reaction described in step (2) is carried out in methanol for 8 to 12 hours at room temperature. After the ion exchange reaction is completed, the anion exchange resin is removed by filtration, and methanol is removed by vacuum distillation and vacuum drying to obtain compound A.

7. The method for preparing the heterocyclic amphoteric phosphate monomer according to claim 2, characterized in that, The specific preparation method of step (3) includes: dissolving compound A obtained in step (2) and phosphoric acid in acetone as solvent to form a homogeneous solution, then adding the phosphoric acid solution dropwise to the compound A solution, and using phosphoric acid to perform a ring-opening reaction on the epoxy group in compound A to obtain the novel heterocyclic amphoteric phosphoric acid monomer; The concentration of the reaction system is controlled at 30–50 wt%. The reaction temperature is -10℃ to 10℃; The dropping time is 2-2.5 hours. After the dropping is completed, the reaction continues for 2 hours. After the reaction is completed, acetone and water are removed by vacuum distillation and vacuum drying to obtain amphoteric phosphoric acid monomers containing heterocyclic rings.

8. A phosphoric acid-based water-reducing agent based on the heterocyclic amphoteric phosphoric acid monomer of claim 1, characterized in that, This phosphate-based water-reducing agent is a polymer obtained by free radical copolymerization of carboxylic acid monomers, heterocyclic amphoteric phosphate monomers, and polyether macromonomers under the action of initiators and chain transfer agents, followed by neutralization with liquid alkali and dilution with water. The molar ratio between the polyether macromonomer, the heterocyclic amphoteric phosphate monomer, and the carboxylic acid monomer is 1:(1-4):(1-3); The initiator is a redox initiator.

9. The phosphate-based water-reducing agent according to claim 8, characterized in that, The carboxylic acid monomer is selected from any one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride and their sodium or potassium salts; The weight-average molecular weight of the polyether macromonomer is 1000-5000, specifically selected from any one of allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, methyl allyl polyoxyethylene ether, and ethylene glycol monovinyl polyethylene glycol ether. The chain transfer agent is selected from any one of mercaptoethanol, mercaptoacetic acid, mercaptopropanol, and mercaptopropionic acid, and the amount of chain transfer agent used is 0.5% to 5% of the total molar amount of the reactants.

10. A method for preparing the phosphate-based water-reducing agent according to claim 7 or 8, characterized in that, Includes the following steps: (1) Preparation of base material: Add polyether macromonomer and water to the reactor and stir at room temperature until completely dissolved to obtain base material; (2) Preparation of dropping solution I: Add the reducing agent and chain transfer agent to water and stir evenly to obtain dropping solution I; (3) Preparation of dropping solution II: Add carboxylic acid monomer and heterocyclic amphoteric phosphate monomer to water and stir evenly to obtain dropping solution II; (4) Add the oxidant to the base material and stir for 2 to 10 minutes. Then, add the drop solution I and the drop solution II to the reactor in sequence at 40 to 80°C. After the drop solution is added, continue to keep the reactor warm. (5) After the reaction is complete, neutralize the pH value to 5.0-7.0 with an alkaline solution and dilute with water to a mass fraction of 30-50% to obtain the phosphate-based water-reducing agent.

11. The method for preparing the phosphate-based water-reducing agent according to claim 10, characterized in that, The mass concentration of polyether macromonomer in the substrate described in step (1) is 60%; The reducing agent in step (2) is selected from any one of L-ascorbic acid, sodium sulfite, sodium bisulfite, and sodium silicate. The amount of reducing agent used is 0.5% to 3% of the total molar amount of the reactants; the mass concentration of the added solution I is 50%. The mass concentration of the added solution II in step (3) is 50%; The oxidant used in step (4) is selected from any one of hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate, and the amount of oxidant used is 2-6% of the total molar amount of the monomers in the reaction; the dropping time of the dropping solution II is 2-5 hours, the dropping time of the dropping solution I is 2.5-6 hours, and the dropping time of the dropping solution I is at least 0.5 hours longer than that of the dropping solution II; the heat preservation reaction time is at least 1 hour; The alkaline solution in step (5) has a mass fraction of 50%, and the alkaline solution is an aqueous solution of a monovalent or divalent metal hydroxide.

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