Cationic polyether macromonomer, preparation method thereof and concrete superplasticizer using cationic polyether macromonomer

Abstract

The invention discloses a cationic polyether macromonomer, a preparation method thereof and a concrete superplasticizer using the cationic polyether macromonomer. The concrete super plasticizer is obtained by copolymerizing a cationic polyether macromonomer, an unsaturated carboxylic acid monomer, an unsaturated phosphoric acid monomer and an unsaturated polyether macromonomer, wherein the cationic polyether macromonomer is prepared by the following steps: firstly, dissolving unsaturated acid and a hydroxyl / amino substituted imidazole compound in a solvent; performing esterification reaction in the presence of a polymerization inhibitor and a catalyst to obtain a compound A; then carrying out quaternization reaction and anion exchange reaction on the compound A and halogenated alcohol to obtain an initiator without halogen ions; and finally, carrying out continuous ethoxylation reaction on the initiator and an epoxy compound in the presence of a catalyst to obtain the cationic polyether macromonomer. The superplasticizer prepared by the invention is high in dispersion speed, has excellent dispersity and slump loss resistance, can reduce viscosity in high-strength concrete, and shows good workability, and the hardened concrete has good mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, and in particular to a cationic polyether macromonomer, a preparation method thereof and a concrete superplasticizer using the same. Background Art

[0002] With the continuous development of my country's infrastructure industry, the scale of large-scale civil engineering projects has continued to expand. The emergence of important buildings with special functional requirements such as high-rise buildings, cross-river bridges, and high-speed rail tunnels requires concrete to have higher strength. High-strength concrete has been widely used in these special buildings due to its advantages such as high durability, low energy consumption, and reduced costs. However, it also has the characteristics of high adhesive and low water-binder ratio, which leads to high viscosity, slow flow rate, and difficulty in pumping. The methods to reduce the viscosity of high-strength concrete are currently mainly through increasing the amount of water reducer, using high-quality mineral admixture powder, and optimizing particle grading.

[0003] Patent CN116622034A discloses a slow-release viscosity-reducing polycarboxylic acid water-reducing agent for high-strength concrete and its preparation method. Under the combined action of hydrophobic long side chain unsaturated polyether macromonomers, unsaturated acid monomers, unsaturated ester monomers and unsaturated amide monomers, the workability of concrete can be improved and can be used for C60 concrete.

[0004] Patent CN107337782B uses thiophene as the main chain, and the substituents of thiophene are reacted to prepare a water reducer containing a sulfonic acid adsorption group and a polyethylene glycol long side chain, which is used for cement-based materials for low-temperature construction.

[0005] Patent CN111393583B uses aminopropanesulfonic acid inner salt type amphoteric monomers to prepare amphoteric concrete water reducers, which solves the problems of self-stability of existing water reducers and difficulty in regulating the content of cationic monomers, and has high water reduction rate and high anti-mud effect.

[0006] The above patents report some water reducers for concrete, which achieve the anti-clay effect of water reducers and reduce concrete viscosity and improve the workability of concrete by adjusting and optimizing the molecular structure. However, in actual production applications, the viscosity reduction effect on high-strength or ultra-high-strength concrete is very limited, and the strength of concrete cannot be improved. Summary of the invention

[0007] In order to solve the problems of high viscosity, slow flow rate and poor workability in concrete, especially the limited viscosity reduction effect of high-strength or ultra-high-strength concrete, the present invention provides a cationic polyether macromonomer, a preparation method thereof and a concrete superplasticizer using the same. The superplasticizer is prepared by polymerization of carboxylic acid, phosphoric acid small monomers and a novel cationic polyether macromonomer, has good dispersibility and collapse retention, can reduce viscosity and improve workability in high-strength or ultra-high-strength concrete.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] A cationic polyether macromonomer, the structure of which is shown in general formula (I):

[0010]

[0011] Wherein R1 represents H or an alkyl group with 1 to 4 carbon atoms; X represents -NH- or -O-, m is an integer of 2 to 4, n is an integer in the range of 2 to 6, and m and n are independent of each other; R2 represents a substituent in different positions and quantities, and the substituent is H or an alkyl group with 1 to 4 carbon atoms; x is an integer of 1 to 5, y is an integer of 10 to 40, and x and y are independent of each other.

[0012] The present invention also provides a method for preparing the above-mentioned cationic polyether macromonomer, comprising the following steps:

[0013] (1) Preparation of compound A: an unsaturated acid and a hydroxyl / amino substituted imidazole compound are dissolved in solvent I, and then inhibitor I and catalyst I are added to obtain compound A through esterification reaction;

[0014] (2) Preparation of an initiator: subjecting the compound A obtained in step (1) to a quaternization reaction and an anion exchange reaction with a halogenated alcohol to obtain an initiator free of halogen ions;

[0015] (3) Preparation of cationic polyether macromonomer: the initiator obtained in step (2) and the epoxy compound are subjected to continuous ethoxylation reaction in the presence of catalyst II to obtain the cationic polyether macromonomer; the product can be further used as an initiator to react with the epoxy compound to obtain the product, which is the cationic polyether macromonomer;

[0016] The weight average molecular weight of the cationic polyether macromonomer is 500-4000.

[0017] The molar ratio of the unsaturated acid to the hydroxyl / amino substituted imidazole compound in step (1) is (1-1.05):1;

[0018] The molar ratio of compound A to halogenated alcohol in step (2) is 1:(1.05-1.20);

[0019] The epoxy compound in step (3) is a mixture of propylene oxide and ethylene oxide, and the molar ratio of the initiator, propylene oxide and ethylene oxide is 1:(1-5):(10-50).

[0020] Furthermore, the unsaturated acid in step (1) of the present invention is selected from any one of acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, and citraconic acid, or a mixture of the above.

[0021] Furthermore, the structure of the hydroxyl / amino substituted imidazole compound in step (1) of the present invention is represented by the general formula (II):

[0022]

[0023] In formula (II), the substituent R is aminoethyl, aminopropyl, aminobutyl, hydroxyethyl, hydroxypropyl or hydroxybutyl, the substituent A is at any position of the 2, 4, or 5 position on the imidazole ring, and the substituent A is a hydrogen atom or an alkyl group of 1 to 4 carbon atoms, specifically a methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl group; further, the hydroxyl / amino substituted imidazole compound is selected from any one of N-aminoethyl imidazole, N-aminopropyl imidazole, N-aminobutyl imidazole, N-hydroxyethyl imidazole, N-hydroxypropyl imidazole, and N-hydroxybutyl imidazole.

[0024] Furthermore, the inhibitor I in step (1) of the present invention is selected from any one of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol, and 2-tert-butylhydroquinone, or a mixture of more than one thereof, and the amount of the inhibitor I is 0.01-5% of the total mass of the reactants;

[0025] The catalyst I is selected from any one of sulfuric acid, phosphoric acid, oxalic acid, and p-toluenesulfonic acid or a mixture of more than one of them, and the amount of the catalyst I is 0.1-5% of the total mass of the reactants;

[0026] The solvent I is an organic solvent, specifically any one selected from acetone, ethyl acetate, acetonitrile, and dichloromethane, or a mixture of more than one thereof. During the reaction, the solvent can be controlled to reflux normally.

[0027] Furthermore, in step (1) of the present invention, the esterification reaction temperature is 50-80° C., the reaction time is 10-40 h, and after the esterification reaction is completed, unreacted acrylic acid and solvent are removed by reduced pressure distillation.

[0028] Furthermore, the halohydrin in step (2) of the present invention is a n-alkyl alcohol having 2 to 6 carbon atoms and a terminal halogen atom, wherein the halogen atom is a fluorine, chlorine or bromine atom.

[0029] Furthermore, in step (2) of the present invention, the compound A is subjected to a quaternization reaction with a halogenated alcohol in a solvent II, wherein the solvent II is selected from any one of methanol, ethanol, ethyl acetate and acetone, the quaternization reaction temperature is 60-100° C., and the reaction time is 12-24 h.

[0030] Furthermore, the bottom viscous liquid collected after the quaternization reaction in step (2) of the present invention is a crude product, and after adding methanol and anion exchange resin, after anion exchange reaction, filtering and purification, an initiator free of halide ions is obtained; wherein the molar ratio of anions in the anion exchange resin to halide ions in the viscous liquid is (20-60):1, the anion exchange reaction temperature is room temperature, and the ion exchange reaction time is 8-12h; wherein the filtering and purification method is: filtering to remove the ion exchange resin, and distilling under reduced pressure to remove the solvent and purify the low-boiling impurities in the crude product, and the low-boiling impurities include halogenated alcohols, etc.

[0031] Furthermore, the catalyst II in step (3) of the present invention is a double metal cyanide, wherein the double metal is Fe(II), Fe(III), C O (II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V); the molar ratio of the initiator to the catalyst II is 1:(0.001-0.50).

[0032] Furthermore, the specific operation of step (3) of the present invention includes: firstly adding the initiator and the catalyst II into the high temperature and high pressure reactor, and performing the vacuum pumping-nitrogen filling operation, the vacuum pumping pressure is not higher than -0.9 MPa, the nitrogen filling pressure is not higher than 0.10 MPa, the vacuum pumping-nitrogen filling operation is performed for not less than 3 times, and the nitrogen replacement time for each time is not less than 5 minutes; then adding the epoxy compound into the reactor to carry out the temperature raising and feeding reaction, the reaction temperature is 110-150°C, the reaction pressure is -0.10~+0.50 MPa, and the reaction time is 1-10h; after the feeding is completed, after 0.5-1h of heat preservation reaction, the temperature is lowered and the material is discharged.

[0033] The present invention also provides a concrete superplasticizer using the cationic polyether macromonomer, which is obtained by copolymerizing the cationic polyether macromonomer with an unsaturated carboxylic acid monomer, an unsaturated phosphoric acid monomer, and an unsaturated polyether macromonomer;

[0034] The molar ratio of the unsaturated polyether macromonomer, the cationic polyether macromonomer, the unsaturated phosphoric acid monomer and the unsaturated carboxylic acid monomer is 1:(0.1-0.3):(0.1-0.5):(1-5).

[0035] The unsaturated carboxylic acid monomer is selected from any one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid.

[0036] The unsaturated phosphoric acid monomer is selected from any one of hydroxyethyl methacrylate phosphate, hydroxypropyl methacrylate phosphate, hydroxyethyl acrylate phosphate and hydroxypropyl acrylate phosphate.

[0037] The unsaturated polyether macromonomer is selected from any one of allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, methyl allyl polyoxyethylene ether and ethylene glycol monovinyl polyethylene glycol ether, and has a weight average molecular weight of 1000-5000.

[0038] Furthermore, the weight average molecular weight of the concrete superplasticizer of the present invention is 15000-50000.

[0039] Furthermore, the method for preparing a concrete superplasticizer according to the present invention comprises the following steps:

[0040] (1) preparing a base material: adding an unsaturated polyether macromonomer, a cationic polyether macromonomer, and water into a reactor, and stirring at room temperature until they are completely dissolved to obtain a base material;

[0041] (2) preparing a dropwise addition liquid A: adding a reducing agent and a chain transfer agent into water and stirring the mixture to obtain a dropwise addition liquid A;

[0042] (3) preparing a dropwise addition liquid B: adding an unsaturated carboxylic acid monomer and an unsaturated phosphoric acid monomer into water and stirring the mixture to obtain a dropwise addition liquid B;

[0043] (4) adding an oxidant to the base material obtained in step (1), stirring for 5 to 10 minutes, and sequentially adding dropwise liquid A and dropwise liquid B to the reactor at 40 to 80° C., and performing a heat-insulating reaction after the dropwise additions are completed; after the reaction is completed, neutralizing with an alkaline solution having a mass fraction of 20 to 50% to a pH value of 5.0 to 7.0, and cooling to room temperature to obtain the concrete superplasticizer.

[0044] Furthermore, the reducing agent in step (2) of the present invention is selected from any one of L-ascorbic acid, sodium sulfite, sodium bisulfite, and Rongalite, and the amount of the reducing agent is 0.5-3% of the total molar amount of the reaction monomers;

[0045] The chain transfer agent is selected from any one of mercaptoethanol, mercaptoacetic acid, mercaptopropanol, and mercaptopropionic acid, and the amount of the chain transfer agent is 0.5-5% of the total molar amount of the reaction monomers;

[0046] The oxidant in step (4) is selected from any one of hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate, and the amount of the oxidant is 2-6% of the total molar amount of the reaction monomers.

[0047] Furthermore, in step (4) of the present invention, the dripping time of the droplet A is 2.5 hours to 5.5 hours, and the dripping time of the droplet B is 2 hours to 5 hours; and the heat preservation reaction time is 1 to 2 hours.

[0048] Furthermore, the alkaline solution in step (4) of the present invention is an aqueous solution of a hydroxide of a positive monovalent or positive divalent metal.

[0049] Furthermore, the concrete superplasticizer obtained in step (4) of the present invention has a solid content of 25-50%.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The cationic polyether macromonomer prepared by the present invention enriches the structure of the polyether macromonomer and has a high degree of flexible design.

[0052] (2) The present invention increases the molecular weight of conventional cationic small monomers and the molecular weight is adjustable. At the same time, the hydrophilic and hydrophobic ratios in the chain segments can also be adjusted, thereby increasing the hydrophilicity and hydrophobicity of the structure, achieving the purpose of controllable air entrainment, reducing the surface tension of water, reducing the viscosity of the concrete, and improving workability.

[0053] (3) The cationic polyether macromonomer in the present invention can improve the limitation that the existing water reducer molecules can only act on positively charged particles, act on more raw material particles, increase the effective adsorption amount, and achieve a high dispersion effect.

[0054] (4) The introduction of an appropriate amount of cations in the present invention can promote the early hydration of cement, significantly improve the early strength and promote the hydration process of cement, and is suitable for high-strength concrete and can improve the early strength of concrete; at the same time, the superplasticizer of the present invention does not contain halide ions, which can eliminate the negative impact of halide ions on the corrosion of reinforced concrete.

[0055] (5) The superplasticizer prepared by the present invention has a fast dispersion speed, excellent dispersibility and slump retention, can reduce viscosity in high-strength concrete, exhibits good workability, and has good mechanical properties of hardened concrete. DETAILED DESCRIPTION

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] The weight average molecular weight of the polymer in the present invention is determined by gel permeation chromatography (gel column: Shodex SB806+803 chromatographic columns connected in series; eluent: 0.1M NaNO3 aqueous solution; mobile phase speed: 0.8mL / min; injection: 20μL of 0.5% aqueous solution; detector: Shodex RI-71 differential refractometer; standard: polyethylene glycol GPC standard (Sigma-Aldrich molecular weight 1010000, 478000, 263000, 118000, 44700, 18600, 6690, 1960, 628, 232).

[0058] (I) Preparation of initiator

[0059] Preparation Example 1

[0060] 73.44 g (1.02 mol) of acrylic acid and 111.15 g (1 mol) of 1-(2-aminoethyl)imidazole were dissolved in toluene, and 0.37 g of hydroquinone and 1.85 g of p-toluenesulfonic acid were added. After esterification at 80° C. for 10 h, unreacted acrylic acid and solvent were removed by reduced pressure distillation to obtain compound A1;

[0061] 165.15 g (1 mol) of compound A1 and 132.46 g (1.06 mol) of 2-bromoethanol were dissolved in ethyl acetate, and refluxed at 80°C for 12 h. After the reaction, the yellow-brown viscous liquid at the bottom was collected and washed with ethyl acetate for multiple times to obtain an ionic liquid. 116.55 g (0.50 mol) of the above ionic liquid was dissolved in methanol, and an anion exchange reaction was carried out on the ionic liquid with 10 times the molar amount of sulfate anion exchange resin. The reaction was stirred at room temperature for 8 h, the ionic resin was filtered out, and the solvent and excess 2-bromoethanol were removed by reduced pressure to obtain a halide-free initiator SIM1.

[0062] Preparation Example 2

[0063] 87.72 g (1.02 mol) of methacrylic acid and 112.13 g (1 mol) of 1-(2-hydroxyethyl)imidazole were dissolved in toluene, and 0.30 g of p-hydroxyanisole and 2.0 g of concentrated sulfuric acid were added. After esterification at 70° C. for 20 h, unreacted methacrylic acid and the solvent were removed by reduced pressure distillation to obtain compound A2.

[0064] 181.13 g (1 mol) of compound A2 and 143.46 g (1.05 mol) of 6-chloro-1-hexanol were dissolved in ethyl acetate, and refluxed at 90°C for 12 h. After the reaction, the yellow-brown viscous liquid at the bottom was collected and washed with ethyl acetate for multiple times to obtain an ionic liquid. 116.55 g (0.50 mol) of the above ionic liquid was dissolved in methanol, and an anion exchange reaction was carried out on the ionic liquid with 10 times the molar amount of sulfate anion exchange resin, and the reaction was stirred at room temperature for 8 h. The ionic resin was filtered to remove the ionic resin, and the solvent and excess 6-chloro-1-hexanol were removed by reduced pressure to obtain a halide-free initiator SIM2.

[0065] (II) Preparation of cationic polyether macromonomer

[0066] The specific preparation method includes: firstly adding an initiator and a catalyst II into a high temperature and high pressure reactor, and performing a vacuum pumping-nitrogen filling operation, wherein the vacuum pumping pressure is not higher than -0.9 MPa, the nitrogen filling pressure is not higher than 0.10 MPa, the vacuum pumping-nitrogen filling operation is performed for not less than 3 times, and each nitrogen replacement time is not less than 5 minutes; then adding an epoxy compound into the reactor to carry out a temperature-raising and material-passing reaction, the reaction temperature is 110-150°C, the reaction pressure is -0.10~+0.50 MPa, and the reaction time is 1-10 hours; after the material passing is completed, after 0.5-1 hour of heat preservation reaction, the temperature is lowered and the material is discharged.

[0067] Synthesis example 1

[0068] 153.1 g (0.5 mol) of initiator SIM1 and 0.04 g of Zn-Co (III) bimetallic catalyst were added to a 2L high-temperature and high-pressure reactor. After three nitrogen replacements, the temperature was raised to 110°C. 29 g (0.5 mol) of propylene oxide was slowly introduced into the reactor, and then 318 g (7.23 mol) of ethylene oxide was introduced. After the introduction was completed, the temperature was kept for 0.5 h, and then the temperature was lowered, degassed, and the material was discharged to obtain imidazole cationic polyether SIM1-1k. The weight average molecular weight was 905 as measured by aqueous gel permeation chromatography.

[0069] Synthesis example 2

[0070] 250 g of SIM1-1k polyether was added to a 2L high-temperature and high-pressure reactor. After three nitrogen replacements, the temperature was raised to 120°C. 500 g of ethylene oxide was introduced into the reactor. After the introduction was completed, the temperature was kept warm for 40 minutes, and then the temperature was lowered, degassed, and the material was discharged to obtain imidazole cationic polyether SIM1-3k. The weight average molecular weight was 2812 as determined by aqueous gel permeation chromatography.

[0071] Synthesis example 3

[0072] 189.13 g (0.5 mol) of initiator SIM2 and 0.06 g of Cr(III)-Mn(II) bimetallic catalyst were added to a 2L high temperature and high pressure reactor. After three nitrogen replacements, the temperature was raised to 125°C. 29 g (1.5 mol) of propylene oxide was slowly introduced into the reactor, followed by 227 g (5.16 mol) of ethylene oxide. After the introduction was completed, the temperature was kept constant for 1 hour, then the temperature was lowered, degassed, and the material was discharged to obtain imidazole cationic polyether SIM2-1k. The weight average molecular weight was 725 as determined by aqueous gel permeation chromatography.

[0073] Synthesis example 4

[0074] 250 g of SIM2-1k polyether was added to a 2L high temperature and high pressure reactor. After three nitrogen replacements, the temperature was raised to 130°C. 500 g of ethylene oxide was introduced into the reactor. After 1 hour after the introduction, the temperature was lowered, degassed and the material was discharged to obtain imidazole cationic polyether SIM2-3k. The weight average molecular weight was 2438 as determined by aqueous gel permeation chromatography.

[0075] (III) Preparation of superplasticizer

[0076] (1) Preparation of base material: adding unsaturated polyether macromonomer, cationic polyether macromonomer and water into a reactor, and stirring at room temperature until completely dissolved;

[0077] (2) Preparation of dropwise solution A: Add reducing agent and chain transfer agent into water and stir evenly;

[0078] (3) preparing dropwise solution B: adding unsaturated carboxylic acid monomer and unsaturated phosphoric acid monomer into water and stirring evenly;

[0079] (4) adding the oxidant to the base material, stirring for 5-10 minutes, and sequentially adding dropwise solution A and dropwise solution B to the reactor at 40-80° C., and then carrying out the reaction under heat preservation after the addition is completed;

[0080] The addition time of dropwise addition liquid B is 2h~5h, the addition time of dropwise addition liquid A is 2.5h~5.5h, and the heat preservation reaction time is 1~2h;

[0081] (5) After the reaction is completed, neutralize with an alkali solution with a mass fraction of 20-50% to a pH value of 5.0-7.0, and cool to room temperature to obtain a phosphoric acid-based water reducer.

[0082] The water reducers of Examples 1-4 and Comparative Examples 1-4 were prepared according to the above steps. The specific material proportions are shown in Table 1, Comparative Example SPC-2 Red Wall High Efficiency Water Reducer CSP-13 Water Reducer.

[0083] Table 1 Material ratio of water reducing agent in Example and Comparative Example

[0084]

[0085]

[0086] Table 2 Reaction conditions parameters of water reducing agent in examples and comparative examples

[0087]

[0088] (I) Cement paste fluidity test

[0089] The cement paste fluidity test was carried out in accordance with GB / T8077-2023, and the prepared superplasticizer was tested for the paste fluidity: the water-cement ratio w / c was 0.29, the superplasticizer solid content was 0.13-0.15% (based on cement mass), and the results are shown in Table 2.

[0090] Table 2 Superplasticizer paste fluidity in cement

[0091]

[0092] Note: Ratio R = 1min pure slurry fluidity / 4min pure slurry fluidity

[0093] It can be seen from the test results in Table 2 that the superplasticizer samples SPI-1 to 4 in the present invention have a faster dispersion speed for cement at a lower dosage. By comparing the fluidity of the samples after stirring for 1 minute and 4 minutes, it can be found that the fluidity of SPI-1 to 4 after stirring for 1 minute can reach more than 93% of that of 4 minutes; the corresponding comparative example 2 can only reach about 78% at a higher dosage. The SPI-1 to 4 samples have good dispersibility and good slump retention effect, while the dispersion ability of the comparative example is still slightly poor when the dosage is 1-2 higher, and the loss over time is large. The above tests show that it has the advantage of fast dispersion under low water-cement ratio conditions, and is expected to be used in high-strength concrete systems. (II) Test on the influence of superplasticizer on the performance of freshly mixed concrete

[0094] According to the concrete experiment, the effect of superplasticizer on the performance of fresh concrete was tested by the method specified in GB / T50080-2016 "Test method for performance of ordinary concrete mixtures". The solid content of superplasticizer and reference sample was 0.22%, the test temperature was 25°C, the humidity was 80%, Conch cement (PO 42.5R) was selected, and the proportion of concrete materials is shown in Table 5.

[0095] Table 3 Concrete raw material ratio

[0096]

[0097] Table 4 Performance test of superplasticizer in concrete

[0098]

[0099]

[0100] From the concrete test results in Table 4, it can be seen that Examples SPI-1 to 4 have the largest initial and 60-min slump and expansion, indicating that the superplasticizer of the present invention has higher water reduction and slump retention performance, and at the same time has the characteristics of significantly shortened flow time compared with the comparative example, indicating that the concrete prepared with SPI superplasticizer has low viscosity, short flow time, good fluidity, no segregation and bleeding and bottoming phenomenon, excellent workability, and is suitable for preparing high-strength concrete. In addition, the water reducer in the present invention contains a certain hydrophobic ratio component in the molecule, so that the concrete has a certain air content, but has no negative impact on the 28-day strength.

[0101] The preferred embodiments of the present invention are described in detail above, but are not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A cationic polyether macromonomer, characterized in that: Its structure is shown in general formula (Ⅰ): Wherein R1 represents H or an alkyl group with 1 to 4 carbon atoms; X represents -NH- or -O-, m is an integer of 2 to 4, n is an integer in the range of 2 to 6, and m and n are independent of each other; R2 represents a substituent in different positions and quantities, and the substituent is H or an alkyl group with 1 to 4 carbon atoms; x is an integer of 1 to 5, y is an integer of 10 to 40, and x and y are independent of each other.

2. A method for preparing the cationic polyether macromonomer according to claim 1, characterized in that: The steps include: (1) Preparation of compound A: an unsaturated acid and a hydroxyl / amino substituted imidazole compound are dissolved in solvent I, and then inhibitor I and catalyst I are added to obtain compound A through esterification reaction; (2) Preparation of an initiator: subjecting the compound A obtained in step (1) to a quaternization reaction and an anion exchange reaction with a halogenated alcohol to obtain an initiator free of halogen ions; (3) Preparation of cationic polyether macromonomer: the initiator obtained in step (2) and the epoxy compound are subjected to continuous ethoxylation reaction in the presence of catalyst II to obtain the cationic polyether macromonomer; The weight average molecular weight of the cationic polyether macromonomer is 500-4000; The molar ratio of the unsaturated acid to the hydroxyl / amino substituted imidazole compound in step (1) is (1-1.05):1; The molar ratio of compound A to halogenated alcohol in step (2) is 1:(1.05-1.20); The epoxy compound in step (3) is a mixture of propylene oxide and ethylene oxide, and the molar ratio of the initiator, propylene oxide and ethylene oxide is 1:(1-5):(10-50).

3. The method for preparing a cationic polyether macromonomer according to claim 2, characterized in that: The unsaturated acid in step (1) is selected from any one of acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, and citraconic acid, or a mixture of the above; The structure of the hydroxyl / amino substituted imidazole compound is shown in the general formula (II): In formula (II), the substituent R is aminoethyl, aminopropyl, aminobutyl, hydroxyethyl, hydroxypropyl or hydroxybutyl, the substituent A is at any position of the 2, 4, or 5 position on the imidazole ring, and the substituent A is a hydrogen atom or an alkyl group of 1 to 4 carbon atoms, specifically methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl; The inhibitor I is selected from any one of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol, and 2-tert-butylhydroquinone, or a mixture of more than one thereof, and the amount of the inhibitor I is 0.01-5% of the total mass of the reactants; The catalyst I is selected from any one of sulfuric acid, phosphoric acid, oxalic acid, and p-toluenesulfonic acid or a mixture of more than one of them, and the amount of the catalyst I is 0.1-5% of the total mass of the reactants; The solvent I is an organic solvent.

4. The method for preparing a cationic polyether macromonomer according to claim 3, characterized in that: The hydroxyl / amino substituted imidazole compound in step (1) is selected from any one of N-aminoethyl imidazole, N-aminopropyl imidazole, N-aminobutyl imidazole, N-hydroxyethyl imidazole, N-hydroxypropyl imidazole and N-hydroxybutyl imidazole; The solvent I is selected from any one of acetone, ethyl acetate, acetonitrile and dichloromethane or a mixture of more than one of them.

5. The method for preparing a cationic polyether macromonomer according to claim 2, characterized in that: The halohydrin in step (2) is an n-alkyl alcohol having 2 to 6 carbon atoms and a terminal halogen atom, wherein the halogen atom is a fluorine, chlorine or bromine atom; The compound A and the halogenated alcohol are subjected to quaternization reaction in a solvent II, and the solvent II is selected from any one of methanol, ethanol, ethyl acetate and acetone.

6. The method for preparing a cationic polyether macromonomer according to any one of claims 2 to 5, characterized in that: The esterification reaction temperature in step (1) is 50-80° C., the reaction time is 10-40 hours, and after the esterification reaction is completed, unreacted acrylic acid and solvent are removed by reduced pressure distillation; In step (2), the quaternization reaction temperature is 60-100° C. and the reaction time is 12-24 h; The viscous liquid at the bottom collected after the quaternization reaction in step (2) is a crude product, and methanol and anion exchange resin are added, an anion exchange reaction is carried out, and then filtered and purified to obtain an initiator free of halide ions; The molar ratio of anions in the anion exchange resin to halide ions in the viscous liquid is (20-60):1, the anion exchange reaction temperature is room temperature, and the ion exchange reaction time is 8-12 hours.

7. The method for preparing a cationic polyether macromonomer according to claim 6, characterized in that: The specific operation of step (3) includes: firstly adding the initiator and catalyst II into the high temperature and high pressure reactor, and performing vacuum-nitrogen filling operation, wherein the vacuum pressure is not higher than -0.9 MPa, the nitrogen filling pressure is not higher than 0.10 MPa, and the vacuum-nitrogen filling operation is performed for not less than 3 times, and each nitrogen replacement time is not less than 5 minutes; then adding the epoxy compound into the reactor to carry out heating and feeding reaction, the reaction temperature is 110-150°C, the reaction pressure is -0.10~+0.50 MPa, and the reaction time is 1-10 hours; after the feeding is completed, after 0.5-1 hours of heat preservation reaction, the temperature is lowered and the material is discharged; The catalyst II is a double metal cyanide, wherein the double metal is Fe(II), Fe(III), C O (II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V); the molar ratio of the initiator to the catalyst II is 1:(0.001-0.50).

8. A concrete superplasticizer using the cationic polyether macromonomer according to claim 1, characterized in that: The concrete superplasticizer is obtained by copolymerizing the cationic polyether macromonomer with unsaturated carboxylic acid monomers, unsaturated phosphoric acid monomers, and unsaturated polyether macromonomers; The molar ratio of the unsaturated polyether macromonomer, the cationic polyether macromonomer, the unsaturated phosphoric acid monomer, and the unsaturated carboxylic acid monomer is 1: (0.1-0.3): (0.1-0.5): (1-5); The weight average molecular weight of the concrete superplasticizer is 15000-50000.

9. The concrete superplasticizer according to claim 8, characterized in that: The unsaturated carboxylic acid monomer is selected from any one of acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; The unsaturated phosphoric acid monomer is selected from any one of hydroxyethyl methacrylate phosphate, hydroxypropyl methacrylate phosphate, hydroxyethyl acrylate phosphate and hydroxypropyl acrylate phosphate; The unsaturated polyether macromonomer is selected from any one of allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, methyl allyl polyoxyethylene ether and ethylene glycol monovinyl polyethylene glycol ether, and has a weight average molecular weight of 1000-5000.

10. A method for preparing the concrete superplasticizer according to claim 8 or 9, characterized in that: The steps include: (1) preparing a base material: adding an unsaturated polyether macromonomer, a cationic polyether macromonomer, and water into a reactor, and stirring at room temperature until they are completely dissolved to obtain a base material; (2) preparing a dropwise addition liquid A: adding a reducing agent and a chain transfer agent into water and stirring the mixture to obtain a dropwise addition liquid A; (3) preparing a dropwise addition liquid B: adding an unsaturated carboxylic acid monomer and an unsaturated phosphoric acid monomer into water and stirring the mixture to obtain a dropwise addition liquid B; (4) adding an oxidant to the base material obtained in step (1), stirring for 5 to 10 minutes, and sequentially adding dropwise liquid A and dropwise liquid B to the reactor at 40 to 80° C., and performing a heat-insulating reaction after the dropwise additions are completed; after the reaction is completed, neutralizing with an alkaline solution having a mass fraction of 20 to 50% to a pH value of 5.0 to 7.0, and cooling to room temperature to obtain the concrete superplasticizer.

11. The method for preparing a concrete superplasticizer according to claim 10, characterized in that: The reducing agent in step (2) is selected from any one of L-ascorbic acid, sodium sulfite, sodium bisulfite, and Rongalite, and the amount of the reducing agent is 0.5-3% of the total molar amount of the reaction monomers; The chain transfer agent is selected from any one of mercaptoethanol, mercaptoacetic acid, mercaptopropanol, and mercaptopropionic acid, and the amount of the chain transfer agent is 0.5-5% of the total molar amount of the reaction monomers; In step (4), the oxidant is selected from any one of hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate, and the amount of the oxidant is 2-6% of the total molar amount of the reaction monomers; the alkaline solution is an aqueous solution of a positive monovalent or divalent metal hydroxide; In step (4), the dripping time of the droplet A is 2.5h to 5.5h, and the dripping time of the droplet B is 2h to 5h; the heat preservation reaction time is 1 to 2h; and the solid content of the concrete superplasticizer is 25-50%.

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