Long-acting stable slump-retaining phosphate water reducer and preparation method thereof

Abstract

The invention discloses a long-acting stable slump-retaining phosphate water reducer and a preparation method thereof, and belongs to the technical field of concrete admixtures. The method comprises the following steps: carrying out ring-opening reaction on a monomer A and a polyamine monomer B to obtain an amino-containing monomer C; and carrying out one-pot reaction on the amino-containing monomer C, a polyether macromonomer D, a polyether micromonomer E, a catalyst F, phosphorous acid, an aldehyde monomer G and an aldehyde monomer J to obtain the long-acting stable slump-retaining phosphate water reducer. The preparation process is simple and easy to implement industrially, the production cost is low, chloride ions are not introduced, and the long-acting stable slump retaining effect within 3 hours is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete admixtures, and particularly relates to a long-acting and stable slump-retention type phosphoric acid-based water reducer and a preparation method thereof. Background Art

[0002] Water reducers are an important component of high-performance concrete. Although their dosage is not high, they are indispensable. Concrete water reducers can be said to be the simplest, most effective, and most economical technical means to reduce the cement dosage of concrete, improve the utilization rate of industrial waste residues, and improve the strength, workability, and durability of concrete. They are essential materials for modern concrete preparation.

[0003] At present, polycarboxylate water reducers are the mainstream of industry research, with high dosage and excellent performance. They have the advantages of low dosage, high water reduction rate, and good cement adaptability. However, with the rapid development of infrastructure construction, various large-scale and high-end projects have put forward more stringent requirements for the performance of concrete. For example, nuclear power, hydropower, and some high-end concretes require a slump of 80-180 mm for concrete pumping. This poses a great challenge to the technology of concrete admixtures, and requires concrete admixtures to have long-acting and stable slump-retention performance. At present, a large number of engineering practices have shown that there are still certain uncontrollabilities in the long-acting and stable slump-retention of polycarboxylate admixtures, and problems such as over-dosage, bleeding, reverse growth, or inability to maintain for a long time are likely to occur.

[0004] More and more researchers have found that in view of these disadvantages of polycarboxylate admixtures, phosphoric acid-based admixtures with high adsorption have good application prospects in long-acting and stable slump-retention, such as slump-retention at medium and low slumps. At present, many patents and literatures have disclosed the preparation methods and achieved effects of phosphoric acid-based water reducers.

[0005] Patent document CN105504297A reports a phosphorous acid concrete superplasticizer with a polyethyleneimine structure. Such polyether derivatives can be used alone or in combination with sulfonate-based water reducers, polycarboxylate water reducers, etc., and can effectively improve the fluidity and slump-retention performance of concrete, especially outstanding in controlling slump loss. However, a large amount of chloride ions are introduced in its preparation process, which may have a negative impact on the durability of reinforced concrete (such as accelerating the corrosion of steel bars), thus limiting its large-scale popularization and application.

[0006] Ran Qianping et al. (Synthesis, characterization and dispersion properties of aseries of bis(phosphonic acid)amino-terminated polymers[J]. Colloid.Polym.Sci., 2016, 294, 189-194) carried out phosphonylation reaction on amino polyether to synthesize a series of low molecular weight polyether derivatives containing phosphonic acid groups. These polyether derivatives exhibited good slump retention and water reducing properties and were less sensitive to clay. However, amino polyether is expensive, and its water reduction is low and the dosage is high, which limits its large-scale application.

[0007] Patents CN107337788A and CN108033978A synthesized polyphosphate-based polymer admixtures by the method of phosphonylation of polyols or polyether polyols, which can initially achieve stable slump retention of medium and low slump concrete. Its effect is feasible in the laboratory, but the actual engineering application effect is not significant and fails to meet the expected performance; therefore, large-scale promotion has not been achieved and there is room for improvement.

[0008] The above-mentioned patents and articles have disclosed different types of phosphate-based water reducers, which exhibit obvious slump retention and water reducing properties. However, due to various reasons, it is difficult to obtain large-scale application. Summary of the Invention

[0009] Technical problems to be solved: Aiming at the above technical problems, the present invention provides a long-acting and stable slump retention type phosphate-based water reducer and its preparation method. Its preparation process is simple and easy to implement industrially, and the production cost is low. There is no chloride ion introduction, and it has a 3-hour long-acting and stable slump retention effect.

[0010] Technical solution: A preparation method of a long-acting and stable slump retention type phosphate-based water reducer includes the following steps: S1. Carry out ring-opening reaction on monomer A and polyamine monomer B to obtain amino-containing monomer C; S2. Carry out one-pot reaction on amino-containing monomer C, polyether macromonomer D, small monomer E, catalyst F, phosphorous acid, aldehyde monomer G and aldehyde monomer J to obtain the long-acting and stable slump retention type phosphate-based water reducer; Among them, the structure of the monomer A is shown as follows: , where R 1 is H, an alkyl group with C1~C10, NR 1 , OR 2 or O(CH 2 ) s OR 3 , R 1, R 2 , R 3 is an alkyl group of C1-C5, s is an integer of 1-8, R 1 takes any position of ortho, meta or para, and the number is 1-3; X is NR 4 , O or O(CH 2 ) f O, R 4 is an alkyl group of C1-C5, f is an integer of 1-8; Y is an alkyl group of C1-C5; The structure of the polyether macromonomer D is shown as follows: , where Z is NR 5 , O or O(CH 2 ) g O, R 5 is an alkyl group of C1-C5, g is an integer of 1-8; Q is an alkylene group of C2-C6, n = 10-70; R 2 is H or an alkyl group of C1-C10, R 2 takes any position of ortho, meta or para, and the number is 1-3; The structure of the small monomer E is shown as follows: , where R 3 is H or an alkyl group of C1-C10, R 3 takes any position of ortho, meta or para, and the number is 1-3; K is NR 6 , O or O[(CH 2 ) p O] r , R 6 is an alkyl group of C1-C5, p is an integer of 1-8, r is an integer of 1-8; L is H or an alkyl group of C1-C5.

[0011] Preferably, the polyamine monomer B is ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexylenediamine, cyclohexanediamine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine or polyethylenepolyamine.

[0012] Preferably, the aldehyde monomer G is formaldehyde, trioxane or paraformaldehyde.

[0013] Preferably, the aldehyde monomer J is acetaldehyde, propionaldehyde, isobutyraldehyde, butyraldehyde, valeraldehyde, heptaldehyde, pyruvaldehyde, crotonaldehyde, 3-methylbutyraldehyde, hexanal, glycolaldehyde, benzaldehyde, phenylacetaldehyde, octanal, decanal, cyclohexanecarboxaldehyde, 3-hydroxypropionaldehyde, 3-hydroxybutyraldehyde or 2-methylbutyraldehyde.

[0014] Preferably, the Y is an alkyl group of C1-C3.

[0015] Preferably, the R 1 is H or an alkyl group of C1-C5 or OR 2 , and R 2 is an alkyl group of C1-C5.

[0016] Preferably, X is O and Y is methylene.

[0017] Preferably, the molar ratio of the monomer A to the polyamine monomer B is (1-1.5):1.

[0018] Preferably, in S1, the reaction temperature is 80-120 °C and the reaction time is 1-5 h.

[0019] Preferably, the R 2 is H and Z is O.

[0020] Preferably, the QO is a mixture of oxyethylene group and oxypropylene group or oxyethylene group, wherein the molar percentage of oxyethylene group in the mixture is not less than 70%.

[0021] Preferably, the R 3 is H, K is O or O[(CH 2 ) p O] r , p is 2, r is 1 or 2, and L is H.

[0022] Preferably, the catalyst F is concentrated sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, trifluoroethanesulfonic acid, benzenesulfonic acid or p-toluenesulfonic acid.

[0023] Preferably, in S2, the dosage of the catalyst F is 10-20% of the total mass of the reactants in S2.

[0024] Preferably, the aldehyde monomer G is 37 wt% formaldehyde.

[0025] Preferably, taking the molar amount of the monomer A as q, the molar amount of the polyether macromonomer D as j, the molar amount of the small monomer E as t, and the molar amount of the unreacted amino hydrogen of the polyamine monomer B in S1 as k, then q:j = (0.5-3):1, t = (0.2-1.0)j, the molar amount of phosphorous acid is (1-1.2)k, the molar amount of the aldehyde monomer G is (1-1.2)*(q + j + t + k), and the molar amount of the aldehyde monomer J is (0.01-0.05)*(q + j + t).

[0026] Preferably, in S2, the reaction temperature is 100-140 °C, reflux reaction is maintained, and the reaction time is 5-10 h.

[0027] Preferably, in S2, after the one-pot reaction is completed, the reaction product is cooled, the pH value of the reaction product is adjusted to 5-7 with a basic compound, and water is added to adjust the solid content to 20-40% to obtain the long-acting and stable slump-retaining phosphate-based water reducer.

[0028] Preferably, the polyether macromonomer D is obtained by initiating the ring-opening polymerization of alkylene oxides with a benzene derivative containing active hydrogen as an initiator.

[0029] Furthermore, the alkylene oxide is selected from one or more of ethylene oxide, propylene oxide, 1-butylene oxide, 2,3-butylene oxide, 2-methyl-1,2-propylene oxide, and 1-pentylene oxide.

[0030] Furthermore, the alkylene oxide is a mixture of ethylene oxide and propylene oxide, and the molar percentage of ethylene oxide in the mixture is not less than 70%.

[0031] Preferably, the polyether macromonomer D is a polyether chain with a block structure or a random structure.

[0032] Furthermore, the polyether macromonomer D has a block structure.

[0033] The long-acting and stable slump-retaining phosphate-based water reducer prepared by the above method.

[0034] Preferably, the weight-average molecular weight of the water reducer is 4000-15000.

[0035] Beneficial effects: The preparation method of the present invention is simple and easy to operate, which is conducive to industrial implementation; in the present invention, the ring-opening reaction of monomer A and polyamine monomer B is carried out to obtain the amino-containing monomer C. The amino-containing monomer C is a small molecule compound containing primary amine, secondary amine and phenoxy structure at the same time. After the one-pot method, the small molecule compound is further subjected to a polycondensation reaction with the polyether macromonomer D and the small monomer E to form a product with a structural effect containing polyetheramine, thus avoiding the direct use of relatively expensive polyetheramine. Therefore, in the synthesis process of the present invention, the amino-containing polyether is prepared without using expensive amino-terminated polyether, which greatly reduces the synthesis cost; the present invention avoids the use of the traditional method of first synthesizing chlorinated polyether and then carrying out amination, thereby avoiding the introduction of chloride ions. Specific embodiments

[0036] The present invention will be described in detail below through examples. These examples are merely illustrative and do not represent a limitation on the scope of application of the present invention. According to the disclosure herein, those skilled in the art can change the reagents, catalysts and reaction process conditions within the scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

[0037] In the embodiments of the present invention, the molecular weight of the polymer was determined by a gel permeation chromatograph. (Gel column: Shodex SB806 + 803 chromatographic columns in series; eluent: 0.1M NaNO 3 solution; mobile phase velocity: 0.8 ml / min; injection: 20 μl of 0.5% aqueous solution; detector: Shodex RI-71 differential refractive index detector; standard: polyethylene glycol gel permeation chromatography standard sample (Sigma-Aldrich, molecular weights 1010000, 478000, 263000, 118000, 44700, 18600, 6690, 1960, 628, 232) In the embodiments, the parts specified refer to parts by mass, and the addition amounts of other materials are all converted to parts by mass. The aldehyde monomer G is 37 wt% formaldehyde.

[0038] Preparation of polyether macromonomer D. Here, the preparation of D-1 is taken as an example for illustration. D-1 has a weight average molecular weight of 2000, and the initiator is phenol. The preparation method is ethoxylation: Weigh 94 parts of phenol and 3 parts of sodium hydroxide, add the above materials to the reaction kettle, and evacuate the reaction kettle to -0.1 MPa at room temperature. Then, heat the reaction kettle to 100 °C, slowly introduce 30 parts of ethylene oxide. When the pressure in the reaction kettle drops and the temperature rises, it indicates that the reaction starts. Continue to introduce 1876 parts of ethylene oxide. During the feeding process, maintain the temperature of the reaction kettle between 100 and 120 °C and the pressure between 0.05 and 0.4 MPa. After the addition of ethylene oxide is completed, continue to keep warm for about 1 h. When the pressure in the reaction kettle no longer decreases, cool the reaction kettle and discharge the material to obtain a light brownish-yellow liquid. After testing by gel permeation chromatography, the molecular weight is 1979, and the molecular weight distribution is 1.03.

[0039] Similarly, based on the above synthesis method, the following polyethers were prepared. Among them, EO represents ethylene oxide, PO represents propylene oxide, EO / (EO + PO) refers to the molar ratio of ethylene oxide, and the propylene oxide listed in the embodiments is located at the end of the polyether chain segment (i.e., the end far from the initiator structure).

[0040]

[0041] In the monomer A used, X is O, Y is methylene, and its number composition is as follows:

[0042] In the small monomer E used, R 3 is H, and L is H, and its number composition is as follows:

[0043] Example 1

[0044] Weigh 6.01 parts of ethylenediamine, add it into the reaction flask, heat it up to 115 °C with stirring, slowly dropwise add 15.02 parts of A-1, and continue to keep the temperature for reaction for 3 h. After the reaction is completed, remove the heating of the reaction flask, add 80 parts of D-1 and 1.13 parts of small monomer E-1, then successively add 10.22 parts of concentrated sulfuric acid, 24.60 parts of phosphorous acid, 38.52 parts of formaldehyde, and 0.33 parts of acetaldehyde (40 wt%), heat up to 140 °C, and continue the reflux reaction for 5 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 12416, and the molecular weight distribution is 1.43.

[0045] Example 2

[0046] Weigh 27.5 parts of polyethylenepolyamine (CAS No. 68131-73-7), add it into the reaction flask, heat it up to 80 °C with stirring, slowly dropwise add 22.53 parts of A-2, and continue to keep the temperature for reaction for 1.5 h. After the reaction is completed, remove the heating of the reaction flask, add 600 parts of D-7 and 41.4 parts of small monomer E-2, then successively add 131.37 parts of methanesulfonic acid, 54.12 parts of phosphorous acid, 121.34 parts of formaldehyde, and 2.70 parts of isobutyraldehyde, heat up to 125 °C, and continue the reflux reaction for 10 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 4328, and the molecular weight distribution is 1.18.

[0047] Example 3

[0048] Weigh 11.62 parts of hexamethylenediamine, add it into the reaction flask, heat it up to 110 °C with stirring, slowly dropwise add 16.52 parts of A-3, and continue to keep the temperature for reaction for 3.5 h. After the reaction is completed, remove the heating of the reaction flask, add 33 parts of D-2 and 4.00 parts of small monomer E-3, then successively add 11.73 parts of trifluoromethanesulfonic acid, 24.97 parts of phosphorous acid, 40.65 parts of formaldehyde, and 0.16 parts of valeraldehyde, heat up to 100 °C, and continue the reflux reaction for 6 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 6534, and the molecular weight distribution is 1.23.

[0049] Example 4

[0050] Weigh 10.81 parts of p-phenylenediamine, add it into the reaction flask, heat it up to 90 °C with stirring, slowly dropwise add 19.52 parts of A-4, and continue to keep the temperature for reaction for 1 h. After the reaction is completed, remove the heating of the reaction flask, add 195 parts of D-8 and 8.56 parts of small monomer E-1, then successively add 32.75 parts of trifluoroethanesulfonic acid, 25.46 parts of phosphorous acid, 50.40 parts of formaldehyde, and 1.01 parts of pyruvaldehyde, heat up to 135 °C, and continue the reflux reaction for 9.5 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 4551 and the molecular weight distribution is 1.19.

[0051] Example 5

[0052] Weigh 14.62 parts of triethylenetetramine, add it into the reaction flask, heat it up to 105 °C with stirring, slowly dropwise add 18.02 parts of A-5, and continue to keep the temperature for reaction for 4.5 h. After the reaction is completed, remove the heating of the reaction flask, add 40 parts of D-3 and 1.10 parts of small monomer E-2, then successively add 14.75 parts of benzenesulfonic acid, 43.30 parts of phosphorous acid, 60.48 parts of formaldehyde, and 0.43 parts of 3-methylbutyraldehyde, heat up to 110 °C, and continue the reflux reaction for 7 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 14409 and the molecular weight distribution is 1.53.

[0053] Example 6

[0054] Weigh 23.24 parts of pentaethylenehexamine, add it into the reaction flask, heat it up to 100 °C with stirring, slowly dropwise add 15.02 parts of A-6, and continue to keep the temperature for reaction for 2 h. After the reaction is completed, remove the heating of the reaction flask, add 100 parts of D-6 and 9.71 parts of small monomer E-3, then successively add 25.15 parts of p-toluenesulfonic acid, 57.40 parts of phosphorous acid, 78.40 parts of formaldehyde, and 0.26 parts of glycolaldehyde, heat up to 120 °C, and continue the reflux reaction for 8 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 8689 and the molecular weight distribution is 1.37.

[0055] Example 7

[0056] Weigh 7.41 parts of propanediamine, add it into the reaction flask, heat up to 95 °C with stirring, slowly dropwise add 19.52 parts of A-1, and continue to keep the temperature for reaction for 5 h. After the reaction is completed, remove the heating of the reaction flask, add 390 parts of D-4 and 6.11 parts of small monomer E-1, then successively add 67.69 parts of concentrated sulfuric acid, 25.46 parts of phosphorous acid, 55.54 parts of formaldehyde, and 1.56 parts of phenylacetaldehyde, heat up to 130 °C, and continue the reflux reaction for 5.5 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 7232, and the molecular weight distribution is 1.25.

[0057] Example 8

[0058] Weigh 10.22 parts of pentanediamine, add it into the reaction flask, heat up to 110 °C with stirring, slowly dropwise add 16.52 parts of A-2, and continue to keep the temperature for reaction for 3 h. After the reaction is completed, remove the heating of the reaction flask, add 137.5 parts of D-5 and 6.83 parts of small monomer E-2, then successively add 18.82 parts of methanesulfonic acid, 23.78 parts of phosphorous acid, 45.04 parts of formaldehyde, and 0.34 parts of decanal, heat up to 115 °C, and continue the reflux reaction for 7 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 13361, and the molecular weight distribution is 1.49.

[0059] Example 9

[0060] Weigh 11.42 parts of cyclohexanediamine, add it into the reaction flask, heat up to 115 °C with stirring, slowly dropwise add 21.02 parts of A-3, and continue to keep the temperature for reaction for 2.5 h. After the reaction is completed, remove the heating of the reaction flask, add 186.7 parts of D-1 and 10.19 parts of small monomer E-3, then successively add 27.52 parts of trifluoromethanesulfonic acid, 25.58 parts of phosphorous acid, 44.59 parts of formaldehyde, and 1.07 parts of 3-hydroxypropanal, heat up to 105 °C, and continue the reflux reaction for 8.5 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid, adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 7610, and the molecular weight distribution is 1.26.

[0061] Example 10

[0062] Weigh 10.32 parts of diethylenetriamine and add it into the reaction flask. While stirring, heat it up to 120 °C, and slowly dropwise add 18.02 parts of A-4. Then continue the insulation reaction for 4 h. After the reaction is completed, remove the heating of the reaction flask, add 48 parts of D-3 and 1.35 parts of small monomer E-1. Then successively add 11.65 parts of trifluoroethanesulfonic acid, 32.72 parts of phosphorous acid, 52.49 parts of formaldehyde, and 0.47 parts of 2-methylbutyraldehyde. Heat it up to 120 °C and continue the reflux reaction for 7.5 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid. Adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 9673 and the molecular weight distribution is 1.34.

[0063] Comparative Example 1 Weigh 18.93 parts of tetraethylenepentamine and add it into the reaction flask. While stirring, heat it up to 105 °C, and slowly dropwise add 22.53 parts of A-5. Then continue the insulation reaction for 2.5 h. After the reaction is completed, remove the heating of the reaction flask, add 450 parts of D-6 and 0.83 parts of small monomer E-2. Then successively add 88.61 parts of benzenesulfonic acid, 49.61 parts of phosphorous acid, 85.73 parts of formaldehyde, and 0.53 parts of propionaldehyde. Heat it up to 125 °C and continue the reflux reaction for 9 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid. Adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 4197 and the molecular weight distribution is 1.17.

[0064] Comparative Example 2 Weigh 8.82 parts of butanediamine and add it into the reaction flask. While stirring, heat it up to 85 °C, and slowly dropwise add 16.52 parts of A-6. Then continue the insulation reaction for 5 h. After the reaction is completed, remove the heating of the reaction flask, add 165 parts of D-4 and 5.01 parts of small monomer E-3. Then successively add 25.39 parts of p-toluenesulfonic acid, 23.78 parts of phosphorous acid, and 46.99 parts of formaldehyde. Heat it up to 130 °C and continue the reflux reaction for 6.5 h. After the reaction is completed, cool down and discharge to obtain a reddish-brown liquid. Adjust the pH to 5 - 7 with 32 wt% alkali solution, and dilute it with water to a solid content of 30% - 40%. Tested by gel permeation chromatography, the molecular weight is 20743 and the molecular weight distribution is 1.88.

[0065] Comparative Example 3 A commercially available high-performance slump-retention polycarboxylate admixture, purchased from Sika Company, Switzerland.

[0066] Application Example

[0067] The performance of the phosphoric acid-based water reducer in the present invention was evaluated by using concrete tests. The materials used in the application examples were as follows: for every cubic meter of concrete, there were 490 kg of reference cement (P.O 42.5); 60 kg of Huainan Pearl Grade I fly ash; 666 kg of granite gravel (5 - 10 mm); 444 kg of granite gravel (10 - 20 mm); 740 kg of manufactured sand (fineness modulus 2.6); and 132 kg of water.

[0068] Table 1 Test results of the slump of concrete over time:

[0069] From the results in Table 1, it can be seen that the slump of the concrete in each example of the present invention can be stably maintained within 180 minutes, meeting the characteristics of long-term and stable slump retention. For the polycarboxylate slump retention agent used in Comparative Example 3, the initial slump was 16.7 cm, the maximum increased to 21.2 cm, and only 10.8 cm remained after 180 minutes, which easily caused bleeding and segregation of the concrete and was not conducive to construction.

[0070] In summary, the phosphoric acid-based water reducer of the present invention has the performance of long-term and stable slump retention.

Claims

1. A method for preparing a long-lasting, stable and collapse-resistant phosphoric acid-based water reducer, characterized in that: The steps include: S1. performing a ring-opening reaction between monomer A and polyamine monomer B to obtain an amine-containing monomer C; S2. The amino-containing monomer C, the polyether macromonomer D, the small monomer E, the catalyst F, the phosphorous acid, the aldehyde monomer G and the aldehyde monomer J are reacted in one pot to obtain the long-lasting stable collapse-protecting phosphate-based water reducer; Wherein, the structure of the monomer A is as follows: ， Where R1 is H, C1~C10 alkyl, NR 1 , OR 2 or O(CH2) s OR 3 , R 1 , R 2 , R 3 is a C1-C5 alkyl group, s is an integer of 1-8, R1 is in any position of the ortho-ortho pair, and the number is 1-3; X is NR 4 , O or O(CH2) f O, R 4 is a C1-C5 alkyl group, f is an integer of 1-8; Y is a C1-C5 alkyl group; The structure of the polyether macromonomer D is as follows: ， Where Z is NR 5 , O or O(CH2) g O, R 5 is a C1-C5 alkyl group, g is an integer of 1-8; Q is a C2-C6 alkylene group, n=10-70; R2 is H or a C1-C10 alkyl group, R2 is in any position of the ortho-ortho pair, and the number is 1-3; The structure of the small monomer E is shown below: ， Where R3 is H or C1~C10 alkyl, R3 is in any position of the ortho-ortho pair, the number is 1~3; K is NR 6 , O or O[(CH2) p O] r , R 6 is a C1~C5 alkyl group, p is an integer of 1~8, r is an integer of 1~8; and L is H or a C1~C5 alkyl group.

2. The method for preparing a long-acting, stable, collapse-resistant phosphate-based water reducer according to claim 1, characterized in that: The polyamine monomer B is ethylenediamine, propylenediamine, butylenediamine, pentanediamine, hexanediamine, cyclohexanediamine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine or polyethylenepolyamine; the aldehyde monomer G is formaldehyde, trioxymethylene or polyoxymethylene; the aldehyde monomer J is acetaldehyde, propionaldehyde, isobutyraldehyde, butyraldehyde, valeraldehyde, heptaldehyde, methylglyoxal, crotonaldehyde, 3-methylbutyraldehyde, hexanal, ethanolaldehyde, benzaldehyde, phenylacetaldehyde, octanal, decanal, cyclohexylcarboxaldehyde, 3-hydroxypropionaldehyde, 3-hydroxybutyraldehyde or 2-methylbutyraldehyde.

3. The method for preparing a long-acting, stable, collapse-resistant phosphate-based water reducer according to claim 1, characterized in that: The molar ratio of the monomer A to the polyamine monomer B is (1-1.5):

1.

4. The method for preparing a long-acting, stable and collapse-resistant phosphate-based water reducer according to claim 1, characterized in that: The R1 is H or C1~C5 alkyl or OR 2 , R 2 is a C1~C5 alkyl group, X is O, and Y is a methylene group.

5. The method for preparing a long-acting, stable, collapse-resistant phosphate-based water reducer according to claim 1, characterized in that: In S1, the reaction temperature is 80-120° C., and the reaction time is 1-5 h.

6. The method for preparing a long-acting, stable, collapse-resistant phosphoric acid-based water reducer according to claim 1, characterized in that: R2 is H, Z is O, and QO is a mixture of ethylene oxide and propylene oxide or ethylene oxide, wherein the molar percentage of ethylene oxide in the mixture is not less than 70%.

7. The method for preparing a long-acting, stable, collapse-resistant phosphate-based water reducer according to claim 1, characterized in that: R3 is H, K is O or O[(CH2) p O] r , p is 2, r is 1 or 2, and L is H.

8. The method for preparing a long-acting, stable, collapse-resistant phosphoric acid-based water reducer according to claim 1, characterized in that: The catalyst F is concentrated sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, trifluoroethanesulfonic acid, benzenesulfonic acid or p-toluenesulfonic acid; the amount of catalyst F used is 10-20% of the total mass of the reactants in S2.

9. The method for preparing a long-acting, stable, collapse-resistant phosphoric acid-based water reducer according to claim 1, characterized in that: Taking the molar amount of the monomer A as q, the molar amount of the polyether macromonomer D as j, the molar amount of the small monomer E as t, and the molar amount of the unreacted amino hydrogen of the polyamine monomer B in S1 as k, then q:j=(0.5~3):1, t=(0.2~1.0)j, the molar amount of phosphorous acid is (1~1.2)k, the molar amount of the aldehyde monomer G is (1~1.2)*(q+j+t+k), and the molar amount of the aldehyde monomer J is (0.01~0.05)*(q+j+t).

10. The method for preparing a long-acting, stable, collapse-resistant phosphoric acid-based water reducer according to claim 1, characterized in that: In S2, the reaction temperature is 100-140° C., the reflux reaction is maintained, and the reaction time is 5-10 hours.

11. The method for preparing a long-acting, stable, collapse-resistant phosphoric acid-based water reducer according to claim 1, characterized in that: In S2, after the one-pot reaction is completed, the reaction product is cooled, the pH value of the reaction product is adjusted to 5-7 with an alkaline compound, and water is added to adjust the solid content to 20-40%, thereby obtaining the long-acting, stable, collapse-resistant phosphate-based water reducer.

12. The method for preparing a long-acting, stable, collapse-resistant phosphoric acid-based water reducer according to claim 1, characterized in that: The polyether macromonomer D is a polyether chain with a block structure or a random structure.

13. The method for preparing a long-acting, stable and collapse-resistant phosphoric acid-based water reducer according to claim 1, characterized in that: The polyether macromonomer D is obtained by using a benzene derivative containing active hydrogen as an initiator to initiate the ring-opening polymerization of alkylene oxide; the alkylene oxide is selected from one or more of ethylene oxide, propylene oxide, 1-butylene oxide, 2,3-butylene oxide, 2-methyl-1,2-propylene oxide, and 1-pentene oxide.

14. A long-acting, stable, collapse-resistant phosphate-based water reducer prepared by the method according to any one of claims 1 to 13.

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