Cationic polyether macromonomer and application thereof, phosphate water reducer and preparation method of phosphate water reducer

Abstract

The invention relates to the technical field of concrete admixtures, and particularly discloses a cationic polyether macromonomer and application thereof, a phosphate water reducer and a preparation method of the phosphate water reducer, the cationic polyether macromonomer is cationic polyether with an aromatic ring, and the aromatic ring is a pyridine ring or an imidazole ring; the structure of the cationic polyether macromonomer is as shown in (1) or (2): # imgabs0 #. According to the invention, unsaturated carboxylic acid monomer, phosphoric acid monomer, cationic polyether macromonomer and common polyether macromonomer are subjected to copolymerization reaction to obtain the phosphate water reducer. The water reducer has excellent dispersity, slump retaining property and adaptability in cement, and has excellent tolerance to clay such as montmorillonite.

Description

Technical Field

[0001] The present application relates to the field of concrete admixtures, and more specifically, to a cationic polyether macromonomer and its application, a phosphate-based water reducer, and a method for preparing the phosphate-based water reducer. Background Art

[0002] Since its development, polycarboxylate water reducer has been extensively studied and improved by experts from all over the world, and has gradually developed into the third generation of high-performance water reducer. Compared with lignin water reducer and naphthalene water reducer, it has the advantages of good dispersibility, high water reduction rate, low dosage, wide molecular design, and green environmental protection. However, polycarboxylate water reducer is highly sensitive to soil. The soil in sand and gravel aggregates will have a serious negative impact on the dispersibility and slump retention of water reducer, and ultimately affect the workability and mechanical strength of concrete.

[0003] The study found that montmorillonite in the soil has the greatest impact on the dispersion performance of polycarboxylic acid water reducers, mainly because montmorillonite will produce strong surface and intercalation adsorption on polycarboxylic acid water reducers. In order to improve the anti-clay ability of polycarboxylic acids, anti-clay sacrificial agents can be added or the molecular structure of polycarboxylic acid water reducers can be redesigned. The addition of anti-clay sacrificial agents allows the sacrificial agent to preferentially adsorb clay, thereby reducing the adsorption of clay on water reducer molecules. The disadvantage of this method is that the sacrificial agent may have a negative impact on other components when used; the design and optimization of the molecular structure of polycarboxylic acid water reducers can obtain modified polycarboxylic acid water reducers, which weakens the intercalation adsorption of water reducers and clays such as montmorillonite. This method is easier to implement and is less likely to have compatibility issues with other components.

[0004] Studies have shown that the introduction of appropriate zwitterions into polycarboxylic acid molecules and the increase of steric hindrance of the side chain can weaken the adsorption of clay on water reducers. In addition, Plank J team and domestic well-known concrete water reducer research experts have successively reported that water reducers containing phosphoric acid groups have excellent water reduction, slump retention and slow setting effects, and are tolerant to clay. Patent CN113045724B discloses a phosphonic acid-based water reducer containing an indole skeleton structure, which is prepared by reacting an indole-derived polyether intermediate obtained by heterocyclic indole compounds and alkylene oxides, amine monomers, aldehyde monomers and phosphorous acid, solving the compatibility problems of clay and sulfate in current water reducers and concrete aggregates. The amphoteric phosphonate water reducer reported in patent CN114644741B is obtained by condensing quaternary ammonium salt monomers, phosphonate monomers and polyether monomers with aldehyde monomers under acid catalysis through phenolic aldehyde condensation reaction, and the positively charged quaternary ammonium salt in the water reducer gives the water reducer anti-clay properties. Patent CN106117468B also found that the cationic side chain structure in the water reducer can change the charge characteristics in a concrete system with a high clay content, preventing the polyether side chain from being adsorbed into the clay interlayer, and effectively inhibiting the adverse effects of clay on the dispersion flow performance. Patent CN114478943A introduces β-cyclodextrin modified with quaternary ammonium groups into the polycarboxylic acid molecules to increase the cationic charge on the cyclodextrin surface, slowing down the entry of other water reducer molecular side chains into the clay interlayer under multiple effects such as charge interaction and large steric hindrance of cyclodextrin, showing high water reduction and high mud resistance.

[0005] The above patent provides a method to reduce the negative impact of clay on polycarboxylic acid water-reducing agent, but the cationic monomers such as quaternary ammonium salts present in the preparation process will introduce halogen ions accordingly, which may have an adverse effect on the later concrete application; and the use of large steric hindrance monomers has problems such as low reaction degree, and it is difficult to achieve industrialization for the time being. Summary of the invention

[0006] The present application provides a cationic polyether macromonomer and its application, as well as a phosphate-based water reducer and a method for preparing a phosphate-based water reducer. A polyether macromonomer containing a heterocycle and simultaneously carrying a charge is designed and synthesized, which enriches the selection range of polyether monomers for polycarboxylic acid water reducers. Moreover, when introducing cations, halogen ions will not be introduced. Moreover, by structurally designing the polycarboxylic acid molecule, cations containing five-membered or six-membered nitrogen heterocycles are introduced to construct cations, and polyoxyethylene ether is connected to the ends to construct a large steric hindrance structure. Under the joint action of structures such as phosphate, carboxyl and polyether, it exhibits excellent dispersion and slump retention and clay tolerance. The present application uses cationic polyether macromonomers and unsaturated carboxylic acid monomers, phosphoric acid monomers and unsaturated polyether macromonomers to prepare phosphate-based water reducers with good dispersion and slump retention, cement adaptability and good clay adaptability.

[0007] In the first aspect, the present application provides a cationic polyether macromonomer, which adopts the following technical solution:

[0008] A cationic polyether macromonomer, wherein the cationic polyether macromonomer is a cationic polyether with an aromatic ring, wherein the aromatic ring is a pyridine ring or an imidazole ring, and the structure of the cationic polyether macromonomer is as shown in (1) or (2):

[0009]

[0010] Wherein, formula (1) represents a pyridinium cationic polyether macromonomer, m is an integer in the range of 2-6, a is an integer in the range of 0-5, b is an integer in the range of 10-40, and a and b are independent of each other; A represents an olefin of 1-4 carbon atoms; R1 represents different H or an alkyl of 1-4 carbon atoms, and R1 can be on any carbon atom, but in a different position from the olefin group;

[0011] Formula (2) represents an imidazolium cationic polyether macromonomer, n is an integer in the range of 2-6, c is an integer in the range of 0-5, d is an integer in the range of 10-40, and c and d are independent of each other; B represents an olefin of 1-4 carbon atoms; R2 represents different H or an alkyl of 1-4 carbon atoms, and R2 can be on any carbon atom, but different from the position of the olefin group.

[0012] Furthermore, the cationic polyether macromonomer is prepared from raw materials including an initiator, an epoxy compound and a catalyst, the initiator is prepared from raw materials including unsaturated aromatic heterocyclic compounds and halogenated alcohols, and the unsaturated aromatic heterocyclic compounds include unsaturated pyridine compounds and unsaturated imidazole compounds.

[0013] Furthermore, the unsaturated pyridine compounds include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine and their respective alkyl substituents containing 1 to 4 carbon atoms; the unsaturated imidazole compounds include 1-vinylimidazole, 2-vinylimidazole, 3-vinylimidazole, 4-vinylimidazole, 5-vinylimidazole and their respective alkyl substituents containing 1 to 4 carbon atoms.

[0014] Furthermore, the preparation method of the cationic polyether macromonomer comprises the following steps: (1) preparation of an initiator: dissolving an unsaturated aromatic heterocyclic compound and a halogenated alcohol in a solvent, reacting them under heating reflux conditions at a temperature of 60-90°C and a reaction time of 12-48 hours, and collecting a bottom viscous liquid; adding an anion exchange resin and an appropriate solvent, stirring at room temperature for 12-24 hours; filtering to remove the ion resin and removing the solvent and excess halogenated alcohol under reduced pressure to obtain an initiator free of halide ions; (2) preparation of a cationic polyether macromonomer: reacting the initiator and an epoxy compound in the presence of a catalyst at a reaction temperature of 110-150°C, a reaction pressure of -0.09 to +0.50 MPa, and a reaction time of 1-8 hours to obtain a cationic polyether macromonomer.

[0015] Furthermore, in step (1), the halohydrin is a n-alkyl alcohol having 2-6 carbon atoms and a terminal halogen atom, the halogen atom is a fluorine, chlorine or bromine atom, and the molar ratio of the unsaturated aromatic heterocyclic compound to the halohydrin is 1:(1.05-1.20).

[0016] Furthermore, the bottom viscous liquid collected in step (1) is a crude product, and after adding methanol and anion exchange resin, an anion exchange reaction is performed to obtain an initiator free of halide ions; wherein the molar ratio of anions in the anion exchange resin to halide ions in the viscous liquid is (10-50):1, and the ion exchange reaction time is 8-12h.

[0017] Furthermore, in step (2), the epoxy compounds are propylene oxide and ethylene oxide, the molar ratio of the initiator, propylene oxide and ethylene oxide is 1:(0-5):(10-40), and the molar ratio of the initiator to the catalyst is 1:(0.01-0.50).

[0018] Further, the catalyst is an alkaline catalyst or a double metal cyanide catalyst. Further, the alkaline catalyst includes any one of potassium, sodium, potassium methoxide, sodium methoxide, potassium ethoxide, sodium ethoxide, potassium hydroxide, sodium hydroxide, potassium hydride and sodium hydride; in the double metal cyanide catalyst, the bimetal is any two of Fe(II), Fe(III), CO(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V).

[0019] Furthermore, in step (2), nitrogen replacement is first performed for no less than 3 times, and each nitrogen replacement time is no less than 5 minutes.

[0020] Furthermore, the method for preparing the cationic polyether macromonomer further comprises the following steps:

[0021] (3) The cationic polyether macromonomer of step (2) is further reacted with ethylene oxide to obtain a high molecular weight cationic polyether macromonomer.

[0022] The weight average molecular weight of the cationic polyether macromonomer is 800-3000.

[0023] In a second aspect, the present application provides an application of a cationic polyether macromonomer, using the following technical solution:

[0024] An application of a cationic polyether macromonomer, wherein the cationic polyether macromonomer is used for preparing a water reducing agent.

[0025] In a third aspect, the present application provides an application of a cationic polyether macromonomer, using the following technical solution:

[0026] A phosphate-based water reducer prepared from a cationic polyether macromonomer, wherein the phosphate-based water reducer is obtained by copolymerizing an unsaturated polyether macromonomer, a cationic polyether macromonomer, an unsaturated phosphoric acid monomer, and an unsaturated carboxylic acid monomer in a molar ratio of 1:(0.1-0.5):(0.1-0.5):(1-5);

[0027] Wherein, the unsaturated carboxylic acid monomer is selected from any one of acrylic acid, methacrylic acid, itaconic acid, citraconic acid and maleic acid;

[0028] The above unsaturated phosphoric acid monomer has the general structural formula (2) shown below:

[0029]

[0030] Where R5 is H or CH3; when X is C n H 2n When n is a positive integer in the range of 1 to 18; when X is COO-C n H 2n Or when X is CO-NH-C n H 2n When n is a positive integer in the range of 1 to 10;

[0031] The unsaturated polyether macromonomer includes any one of allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, methylallyl polyoxyethylene ether and ethylene glycol monovinyl polyethylene glycol ether.

[0032] Furthermore, the weight average molecular weight of the phosphoric acid-based water reducer is 20,000-50,000; the unsaturated phosphoric acid monomer is selected from any one of 2-acryloyloxyethyl phosphate, 2-acryloyloxypropyl phosphate, 2-methacryloyloxyethyl phosphate, 2-methacryloyloxypropyl phosphate, 2-acrylamidoethyl phosphate, 2-acrylamidopropyl phosphate, 2-acrylamidobutyl phosphate, etc.

[0033] In a fourth aspect, the present application provides an application of a cationic polyether macromonomer, using the following technical solution:

[0034] A method for preparing a phosphoric acid-based water reducer comprises the following steps:

[0035] (1) Preparation of base material: Add unsaturated polyether macromonomer and cationic polyether macromonomer water into a reactor and stir at room temperature until completely dissolved;

[0036] (2) Preparation of dropwise solution A: Add reducing agent and chain transfer agent into water and stir evenly;

[0037] (3) preparing dropwise solution B: adding unsaturated carboxylic acid monomer and unsaturated phosphoric acid monomer into water and stirring evenly;

[0038] (4) Add the oxidant to the base material, stir for 5-10 minutes, add dropwise solution A and dropwise solution B to the reactor in sequence at 40-80° C., and keep the reaction warm for 1-2 hours after the addition is complete;

[0039] (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.

[0040] Furthermore, in step (2), the reducing agent is selected from any one of L-ascorbic acid, sodium sulfite, sodium bisulfite, potassium sulfite, and potassium bisulfite, 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, thioglycolic 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.

[0041] Furthermore, 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 dripping time of the droplet A is (2-5) hours, and the dripping time of the droplet B is (2.5-5.5) hours.

[0042] Furthermore, in step (5), the alkaline solution is an aqueous solution of a hydroxide of a monovalent or divalent metal, and the solid content of the obtained phosphate-based water-reducing agent is 25-50%.

[0043] In summary, this application has the following beneficial effects:

[0044] 1. The present application provides a method for preparing a cationic polyether macromonomer, which broadens the structure of the polyether monomer and develops the monomer structure towards diversification and multifunctionality; the preparation reaction is simple, mild and efficient, and easy to separate and purify.

[0045] 2. The water reducer prepared in the present application is an amphoteric polyelectrolyte, and has an anti-polyelectrolyte effect. Under strong electrolyte and strong alkaline conditions, the molecular structure will not curl, but will expand further, which is beneficial to the adsorption of cement particles by special functional groups in the water reducer. Under the action of carboxylic acid and phosphoric acid groups, the dispersion effect is better and the water reduction rate is higher.

[0046] 3. The presence of aromatic heterocyclic cations can reduce the sensitivity of water reducers to clay. The large steric hindrance effect of aromatic heterocyclics can also weaken the intercalation adsorption of long side chains of polyether in clay to a certain extent, so that the water-reducing and slump-preserving effects are not weakened, thus showing multiple beneficial effects of water reduction, slump-preserving and mud resistance.

[0047] 4. The molecular structure of the water reducer in the present application contains aromatic heterocyclic cations such as imidazole and pyridine, which makes the water reducer have antibacterial and antiseptic effects, can reduce the occurrence of problems such as mold and deterioration during storage and transportation at high temperatures, and can also reduce the use of antibacterial preservatives, save production costs, and reduce the impact of foreign components on the performance of the water reducer; at the same time, the water reducer in the present application does not contain chloride ions, which can eliminate the potential harm caused by chloride ions to the corrosion of reinforced concrete.

[0048] 5. Compared with the introduction of cations by means of quaternary ammonium salts, the cationic polyether macromonomer in the present application introduces cations without introducing halogen anions, thereby avoiding the corrosion effect of halogen anions on steel bars; in addition, heterocyclic structures generally have the problem of poor water solubility. The cationic polyether macromonomer in the present application introduces heterocyclic structures while having excellent water solubility. DETAILED DESCRIPTION

[0049] The present application is further described in detail below with reference to the embodiments.

[0050] The weight-average molecular weight of the polymer in the present application 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).

[0051] Initiator Preparation Example

[0052] Preparation Example 1

[0053] 108.14 g (1 mol) of 1-allylimidazole and 131.21 g (1.05 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 not less than 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 solvent and the excess 2-bromoethanol was removed by decompression to obtain the initiator VIM1 without halide ions.

[0054] Preparation Example 2

[0055] 94.11 g (1 mol) of 1-vinylimidazole and 165.26 g (1.08 mol) of 4-bromo-1-butanol were dissolved in ethyl acetate, and refluxed at 80°C for 18 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. 123.57 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 not less than 20 times the molar amount of sulfate anion exchange resin, and the reaction was stirred at room temperature for 10 h. The ionic resin was filtered to remove the ionic resin, and the solvent and excess 4-bromo-1-butanol were removed by decompression to obtain a halide-free initiator VIM2.

[0056] Preparation Example 3

[0057] 119.16 g (1 mol) of 3-vinyl-2-methylpyridine and 165.26 g (1.20 mol) of 4-bromo-1-butanol were dissolved in acetone, and refluxed at 60°C for 18 h. After the reaction, the yellow-brown viscous liquid at the bottom was collected and washed with acetone for multiple times to obtain an ionic liquid. 136.09 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 not less than 20 times the molar amount of sulfate anion exchange resin, and the reaction was stirred at room temperature for 10 h. The ionic resin was filtered out and the solvent and excess 4-bromo-1-butanol were removed by decompression to obtain a halide-free initiator VIP1.

[0058] Preparation Example 4

[0059] 105.14 g (1 mol) of 4-vinylpyridine and 157.12 g (1.15 mol) of 6-bromo-1-hexanol were dissolved in acetone, and refluxed at 60°C for 24 h. After the reaction, the yellow-brown viscous liquid at the bottom was collected and washed with acetone for multiple times to obtain an ionic liquid. 123.56 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 not less than 30 times the molar amount of sulfate anion exchange resin, and the reaction was stirred at room temperature for 12 h. The ionic resin was filtered to remove the solvent and the excess 6-chloro-1-hexanol was removed by decompression to obtain a halide-free initiator VIP2.

[0060] Example

[0061] Example 1

[0062] 124.6g (0.5mol) of initiator VIM1 and 0.12g (0.005mol) of NaH were added to a 2L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times, each time for no less than 5 minutes. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 58g (1mol) of propylene oxide was slowly introduced into the system, and then 352g (8mol) of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain the aromatic heterocyclic cationic polyether VIM1-1k. The weight average molecular weight was 986 as determined by aqueous gel permeation chromatography.

[0063] Example 2

[0064] Add 250g of VIM1-1k polyether to a 2L high-temperature and high-pressure reactor, replace the air in the system with nitrogen, repeat this operation at least three times, each time for no less than 5 minutes; raise the temperature to 120°C and the pressure to -0.09MPa, introduce 500g of ethylene oxide into the system under this condition, and let the reaction mature for 1h after the introduction is completed. Then cool down, degas, and discharge to obtain the aromatic heterocyclic cationic polyether VIM1-3k, and the weight average molecular weight is 2865 as determined by aqueous gel permeation chromatography.

[0065] Example 3

[0066] 131.6g (0.5mol) of initiator VIM2 and 6g (0.15mol) of KH were added to a 2L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times, each time for no less than 5 minutes. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 145g (2.5mol) of propylene oxide was slowly introduced into the system, and then 220g (5mol) of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain the aromatic heterocyclic cationic polyether VIM2-1k. The weight average molecular weight was 953 as determined by aqueous gel permeation chromatography.

[0067] Example 4

[0068] Add 250g of VIM2-1k polyether to a 2L high temperature and high pressure reactor, replace the air in the system with nitrogen, repeat this operation at least three times, each time for no less than 5 minutes; raise the temperature to 120°C and the pressure to -0.09MPa, introduce 500g of ethylene oxide into the system under this condition, and let the reaction mature for 1h after the introduction. Then cool down, degas, and discharge to obtain the aromatic heterocyclic cationic polyether VIM2-3k, the weight average molecular weight of which is 2865 as determined by aqueous gel permeation chromatography.

[0069] Example 5

[0070] 144.1g (0.5mol) of initiator VIM2 and 0.60g (0.025mol) of NaH were added to a 2L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times, each time for no less than 5 minutes. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 360g (5.90mol) of ethylene oxide was slowly introduced into the system. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain the cationic polyether VIP1-1k containing aromatic heterocycles. The weight average molecular weight was 961 as determined by aqueous gel permeation chromatography.

[0071] Example 6

[0072] Add 250g of VIP1-1k polyether to a 2L high temperature and high pressure reactor, replace the air in the system with nitrogen, repeat this operation at least three times, each time for no less than 5 minutes; raise the temperature to 120°C and the pressure to -0.09MPa, introduce 500g of ethylene oxide into the system under this condition, and let the reaction mature for 1h after the introduction is completed. Then cool down, degas, and discharge to obtain the aromatic heterocyclic cationic polyether VIP1-3k, and the weight average molecular weight is 2792 as determined by aqueous gel permeation chromatography.

[0073] Example 7

[0074] 128.9g (0.5mol) of initiator VIP2 and 6.0g (0.25mol) of NaH were added to a 2L high temperature and high pressure reactor. The air in the system was first replaced with nitrogen. This operation must be repeated at least three times, each time for no less than 5 minutes. The temperature was raised to 120°C and the pressure was -0.09MPa. Under this condition, 87g (1.5mol) of propylene oxide was slowly introduced into the system, and then 220g (5mol) of ethylene oxide was introduced. After the introduction, the reaction was allowed to mature for 1h. Then the temperature was lowered, degassed, and the material was discharged to obtain the aromatic heterocyclic cationic polyether VIP2-1k. The weight average molecular weight was 941 as determined by aqueous gel permeation chromatography.

[0075] Example 8

[0076] Add 250g of VIP2-1k polyether to a 2L high temperature and high pressure reactor, replace the air in the system with nitrogen, repeat this operation at least three times, each time for no less than 5 minutes; raise the temperature to 120°C and the pressure to -0.09MPa, introduce 500g of ethylene oxide into the system under this condition, and let it mature for 1h after the introduction. Then cool down, degas, and discharge to obtain the aromatic heterocyclic cationic polyether VIP2-3k, the weight average molecular weight of which is 2832 as determined by aqueous gel permeation chromatography.

[0077] Application Examples

[0078] The present application provides a method for preparing a phosphate-based water reducer, comprising the following steps:

[0079] (1) Preparation of base material: adding unsaturated polyether macromonomer, cationic polyether macromonomer containing aromatic heterocycle and water into a reactor, and stirring at room temperature until completely dissolved;

[0080] (2) Preparation of dropwise solution A: Add reducing agent and chain transfer agent into water and stir evenly;

[0081] (3) preparing dropwise solution B: adding unsaturated carboxylic acid monomer and unsaturated phosphoric acid monomer into water and stirring evenly;

[0082] (4) adding the oxidant to the base material, stirring for 5-10 minutes, adding dropwise solution A and dropwise solution B to the reactor in sequence at 40-60° C., and then carrying out the reaction at a temperature of 40° C. to keep the temperature constant;

[0083] (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.

[0084] The following is an explanation using a specific application example.

[0085] Application Examples 1-8

[0086] Application Examples 1 to 8 provide a method for preparing a phosphoric acid-based water reducer, comprising the following steps:

[0087] (1) Preparation of base material: Add unsaturated polyether macromonomer and cationic polyether macromonomer water into a reactor and stir at room temperature until completely dissolved;

[0088] (2) Preparation of dropwise solution A: Add reducing agent and chain transfer agent into water and stir evenly;

[0089] (3) preparing dropwise solution B: adding unsaturated carboxylic acid monomer and unsaturated phosphoric acid monomer into water and stirring evenly;

[0090] (4) adding the oxidant to the base material, stirring for 5-10 minutes, and sequentially adding droplet A and droplet B to the reactor at 40-80°C, and then carrying out the heat preservation reaction for 1-2 hours; specifically, adding the oxidant to the base material, stirring for 8 minutes, and sequentially adding droplet A and droplet B to the reactor at 60°C, the droplet A is added for 2 hours, the droplet B is added for 2.5 hours, and then carrying out the heat preservation reaction for 2 hours.

[0091] (5) After the reaction is completed, neutralize with a 20-50% by mass alkali solution to a pH value of 5.0-7.0, cool to room temperature, and obtain a phosphoric acid-based water reducer. Specifically, neutralize with a 30% by mass sodium hydroxide solution to a pH value of 6.0, cool to room temperature, and obtain a phosphoric acid-based water reducer.

[0092] The differences between Application Examples 1-8 are detailed in Table 1, where the numbers below the corresponding substances are their molar amounts. At the same time, according to the above process, comparative application examples 1-2 are provided, and commercially available red wall high-efficiency water reducing agent CSP-13 is provided as a control example.

[0093] Table 1 Application example water reducing agent material ratio

[0094]

[0095]

[0096]

[0097] Performance Testing

[0098] (1) Cement paste fluidity test

[0099] The cement paste fluidity test was carried out in accordance with GB / T8077-2023. The prepared phosphate-based water reducer was tested for the fluidity of the cement paste: 300 g of cement, 87 g of water, and after stirring (slow speed 120 s, stop 15 s, fast 120 s), the cement paste fluidity was measured on a flat glass. The cement specification used was PO 42.5. The results are shown in Tables 2 and 3.

[0100] (2) Test on fluidity of slurry with different montmorillonite content

[0101] The cement paste fluidity test was carried out in accordance with GB / T8077-2023 standard, with 300g of Helin cement, 87g of water, and a certain amount of montmorillonite added. After stirring for 4 minutes, the cement paste fluidity was measured on a flat glass. The cement specification used was PO 42.5. The test results are shown in Table 4.

[0102] Table 2 Fluidity of phosphate-based water reducer in different cement pastes

[0103]

[0104] Table 3 Fluidity of phosphate-based water reducer in different cement pastes (continued)

[0105]

[0106]

[0107] Table 4 Fluidity of phosphate-based water reducer at different montmorillonite dosages

[0108]

[0109] Conch Cement, Onoda Cement, Helin Cement, Jidong Cement and Yadong Cement were used for the pure slurry test respectively. It can be seen from the test results in Tables 2 and 3 that the pure slurry fluidity of the phosphate-based water-reducing agent SPV series provided in this application can be basically maintained at 259-280mm at a dosage of 0.16% in different cements. After 60 minutes, the pure slurry fluidity can still be maintained above 220mm, showing good dispersibility, slump retention and cement adaptability; among them, the phosphate-based water-reducing agent prepared by using high molecular weight cationic macromonomer polyether has better dispersibility. The comparison sample SPC series has a dosage that is 3 points higher, and its dispersibility and slump retention are relatively good in Onoda Cement; its dispersibility and slump retention are average in Conch Cement, Jidong Cement and Yadong Cement, and poor in Helin Cement, indicating that the cement of the comparison sample has poor adaptability. From the analysis of the microscopic molecular structure, the water reducer prepared in the present application is an amphoteric polyelectrolyte, and there is an anti-polyelectrolyte effect. Under strong electrolyte and strong alkaline conditions, the molecular structure will not curl, but will expand further, which is beneficial to the adsorption of cement particles by special functional groups in the water reducer. Under the action of carboxylic acid, phosphoric acid groups, etc., the dispersion effect is better and the water reduction rate is higher. At the same time, the high molecular weight polyether provides a larger spatial structure, which can also effectively prevent the agglomeration of cement particles.

[0110] Phosphoric acid-based water reducers SPV-2 and SPV-7 and comparative samples SPC-1 to 3 were selected from Helin cement to conduct montmorillonite influence experiments, and the test results of the net slurry fluidity are shown in Table 4. When the dosage of SPV-2 and SPV-7 is 0.16%, the montmorillonite is added at 0-1.5%, and the prepared phosphoric acid-based water reducer has a higher dosage of montmorillonite of 1.5%, the initial net slurry fluidity can be maintained above 200mm, and the fluidity is still 170mm after 60min. The influence of montmorillonite on fluidity is much less than that of the comparative samples. When the montmorillonite dosage is 0.5%, the fluidity of most comparative samples is greatly lost after 30min, and there is basically no fluidity afterwards; when the montmorillonite dosage is further increased to 1.0%, they only have the initial fluidity, which shows that montmorillonite has a greater influence on the comparative samples. The presence of cations in the present application can reduce the sensitivity of the water reducer to clay, and the large steric hindrance effect of the aromatic heterocycle can also weaken the intercalation adsorption of the long side chain of the polyether in the clay to a certain extent, so that the water-reducing and slump-preserving effect is not weakened, thereby showing multiple beneficial effects of water reduction, slump preservation and mud resistance.

[0111] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A cationic polyether macromonomer, characterized in that: The cationic polyether macromonomer is a cationic polyether with an aromatic ring, wherein the aromatic ring is a pyridine ring or an imidazole ring, and the structure of the cationic polyether macromonomer is as shown in (1) or (2): Wherein, formula (1) represents a pyridinium cationic polyether macromonomer, m is an integer in the range of 2-6, a is an integer in the range of 0-5, b is an integer in the range of 10-40, and a and b are independent of each other; A represents an olefin of 1-4 carbon atoms; R1 represents different H or an alkyl of 1-4 carbon atoms, and R1 can be on any carbon atom, but in a different position from the olefin group; Formula (2) represents an imidazolium cationic polyether macromonomer, n is an integer in the range of 2-6, c is an integer in the range of 0-5, d is an integer in the range of 10-40, and c and d are independent of each other; B represents an olefin of 1-4 carbon atoms; R2 represents different H or an alkyl of 1-4 carbon atoms, and R2 can be on any carbon atom, but different from the position of the olefin group.

2. A cationic polyether macromonomer according to claim 1, characterized in that: The cationic polyether macromonomer is prepared from raw materials including an initiator, an epoxy compound and a catalyst. The initiator is prepared from raw materials including an unsaturated aromatic heterocyclic compound and a halogenated alcohol. The unsaturated aromatic heterocyclic compound is an unsaturated pyridine compound or an unsaturated imidazole compound.

3. A cationic polyether macromonomer according to claim 2, characterized in that: The unsaturated pyridine compounds include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine and alkyl substituents thereof each having 1 to 4 carbon atoms.

4. A cationic polyether macromonomer according to claim 2, characterized in that: The unsaturated imidazole compounds include 1-vinylimidazole, 2-vinylimidazole, 3-vinylimidazole, 4-vinylimidazole, 5-vinylimidazole and alkyl substituents thereof each having 1 to 4 carbon atoms.

5. A cationic polyether macromonomer according to claim 2, characterized in that: The method for preparing a cationic polyether macromonomer comprises the following steps: (1) preparing an initiator: dissolving an unsaturated aromatic heterocyclic compound and a halogenated alcohol in a solvent, reacting them under heating reflux conditions at a temperature of 60-90° C. and a reaction time of 12-48 hours, and collecting a bottom viscous liquid; adding an anion exchange resin and an appropriate solvent, and stirring at room temperature for 12-24 hours; filtering to remove the ion resin and removing the solvent and excess halogenated alcohol under reduced pressure to obtain an initiator free of halide ions; (2) preparing a cationic polyether macromonomer: reacting the initiator and an epoxy compound in the presence of a catalyst at a reaction temperature of 110-150° C., a reaction pressure of -0.09 to +0.50 MPa, and a reaction time of 1-8 hours to obtain a cationic polyether macromonomer.

6. A cationic polyether macromonomer according to claim 5, characterized in that: In the step (1), the halohydrin is a n-alkyl alcohol having 2 to 6 carbon atoms and a halogen atom at the end, wherein the halogen atom is a fluorine, chlorine or bromine atom, and the molar ratio of the unsaturated aromatic heterocyclic compound to the halohydrin is 1:(1.05-1.20).

7. A cationic polyether macromonomer according to claim 5, characterized in that: In the step (2), the epoxy compounds are propylene oxide and ethylene oxide, the molar ratio of the initiator, propylene oxide and ethylene oxide is 1:(0-5):(10-40), and the molar ratio of the initiator to the catalyst is 1:(0.01-0.50).

8. A cationic polyether macromonomer according to claim 5, characterized in that: The catalyst is a base catalyst or a double metal cyanide catalyst.

9. A cationic polyether macromonomer according to claim 5, characterized in that: The method for preparing the cationic polyether macromonomer further comprises the following steps: (3) The cationic polyether macromonomer of step (2) is further reacted with ethylene oxide to obtain a high molecular weight cationic polyether macromonomer.

10. Use of the cationic polyether macromonomer according to any one of claims 1 to 9, characterized in that: The cationic polyether macromonomer is used for preparing a water reducing agent.

11. A phosphate-based water reducer prepared from the cationic polyether macromonomer according to any one of claims 1 to 9, characterized in that: The phosphate-based water reducer is obtained by copolymerizing an unsaturated polyether macromonomer, a cationic polyether macromonomer, an unsaturated phosphoric acid monomer, and an unsaturated carboxylic acid monomer in a molar ratio of 1: (0.1-0.5): (0.1-0.5): (1-5); Wherein, the unsaturated carboxylic acid monomer is selected from any one of acrylic acid, methacrylic acid, itaconic acid, citraconic acid and maleic acid; The above unsaturated phosphoric acid monomer has the general structural formula (2) shown below: Where R5 is H or CH3; when X is C n H 2n When n is a positive integer in the range of 1 to 18; when X is COO-C n H 2n Or when X is CO-NH-C n H 2n When n is a positive integer in the range of 1 to 10; The unsaturated polyether macromonomer includes any one of allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether, methylallyl polyoxyethylene ether and ethylene glycol monovinyl polyethylene glycol ether.

12. A method for preparing a phosphoric acid-based water reducer as claimed in claim 11, characterized in that: The following steps are involved: (1) Preparation of base material: Add unsaturated polyether macromonomer and cationic polyether macromonomer water into a reactor and stir at room temperature until completely dissolved; (2) Preparation of dropwise solution A: Add reducing agent and chain transfer agent into water and stir evenly; (3) preparing dropwise solution B: adding unsaturated carboxylic acid monomer and unsaturated phosphoric acid monomer into water and stirring evenly; (4) Add the oxidant to the base material, stir for 5-10 minutes, add dropwise solution A and dropwise solution B to the reactor in sequence at 40-80° C., and keep the reaction warm for 1-2 hours after the addition is complete; (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.

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