Preparation method of sulfamic acid water reducer

Abstract

The invention belongs to the technical field of cement admixtures, and particularly relates to a preparation method of a sulfamic acid water reducer. The amide modified sodium lignin sulfonate and the nano silicon dioxide are introduced into the water reducing agent, a hydrophobic main chain of the prepared sulfamic acid water reducing agent contains groups such as phenyl and is connected with various hydrophilic groups such as-SO3Na,-OH,-NH2 and-CONH, and the water reducing agent has good water retention performance due to the synergistic effect of the various groups; the bleeding phenomenon in the concrete can be effectively reduced, and the durability of the concrete is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of cement admixtures, and particularly relates to a preparation method of an amino sulfonic acid-based water reducing agent. Background Art

[0002] A water reducing agent is a concrete admixture that can reduce the mixing water consumption under the condition of maintaining the slump of concrete unchanged. The water reducing agent mainly reduces the attraction between cement particles and disperses the molecules in the cement according to the polar adsorption and polar repulsion effects. Generally, it is a surfactant. After adding the water reducing agent to the concrete, the frost resistance, corrosion resistance, bleeding property, impermeability, mechanical strength and other properties of the concrete can be improved.

[0003] Water reducing agents mainly include naphthalene-based water reducing agents, melamine-based water reducing agents, amino sulfonic acid-based water reducing agents, polycarboxylate-based water reducing agents and other water reducing agents. Although the processes of naphthalene-based and melamine-based water reducing agents are mature, due to their low water reducing rate and poor compatibility with cement, they show many deficiencies in the preparation of high-performance concrete. The application of polycarboxylate-based water reducing agents is greatly restricted because they are incompatible with many admixture components. Amino sulfonic acid-based water reducing agents have become a research hotspot in recent years due to their high water reducing rate and low dosage.

[0004] The Chinese patent application document with the application publication number CN107777906A discloses a preparation method of an amino sulfonic acid-based water reducing agent. This technical solution utilizes industrial phenolic wastewater to prepare a crude phenol, sodium hydroxide, flake alkali and FePO4 solid acid catalyst through the phenolic wastewater to prepare an amino sulfonic acid-based water reducing agent, which shortens the reaction time and improves the raw material conversion rate. However, the hydrophobic molecular chain of the amino sulfonic acid-based water reducing agent molecule is short and the polarity is strong. Although it can effectively disperse cement particles, it is difficult to form a tight, stable and relatively thick adsorption layer to prevent the migration of water, resulting in relatively poor water retention performance when applied to concrete. Therefore, the amino sulfonate superplasticizer is relatively sensitive to the dosage during actual use, and the bleeding and segregation phenomena are serious when the dosage is high, affecting the construction quality. Summary of the Invention

[0005] There is a problem of bleeding and segregation in the existing amino sulfonic acid-based water reducing agent. To solve this problem, the present invention provides a preparation method of an amino sulfonic acid-based water reducing agent.

[0006] To achieve the purpose of the present invention, the following technical solutions are adopted in the present invention: The present invention provides a preparation method of an amino sulfonic acid-based water reducing agent, comprising the following steps: S1: Mix 4-(methylsulfonyl)phenol, phenol, sodium p-aminobenzenesulfonate and water evenly, adjust the pH to 9-11, raise the temperature once, dropwise add an aqueous aldehyde solution, raise the temperature for the second time and react, then dry to obtain the first substance; S2: Mix sodium amide-modified lignosulfonate, the first substance and water evenly, adjust the pH to 9-11 and then react, then dry to obtain the second substance; S3: Mix the second substance and water evenly, dropwise add a nano-silica suspension and react to obtain an amino sulfonic acid-based water reducer.

[0007] By adopting the above technical solution, the present invention introduces sodium amide-modified lignosulfonate and nano-silica into the water reducer. The prepared amino sulfonic acid-based water reducer has a hydrophobic main chain containing groups such as phenyl, and is connected with various hydrophilic groups such as -SO3Na, -OH, -NH2 and -CONH, making the amino sulfonic acid-based water reducer have good water retention and water reduction rate.

[0008] Preferably, in the step S1, the molar ratio of 4-(methylsulfonyl)phenol, phenol to sodium p-aminobenzenesulfonate is (1-1.2):(0.8-1):1.

[0009] By adopting the above technical solution, the amino sulfonic acid-based water reducer prepared by 4-(methylsulfonyl)phenol and phenol within this dosage range has a moderate dispersibility for cement; when the dosage of phenolic substances is small, the number of groups such as benzene rings in the amino sulfonic acid-based water reducer molecule will decrease, the steric hindrance effect between molecules becomes smaller, and the dispersing effect on cement weakens; when the dosage of phenolic substances is large, excessive polymerization is likely to occur, resulting in an increase in the molecular weight of the amino sulfonic acid-based water reducer, which also affects the dispersing performance of cement.

[0010] Preferably, in the step S1, the aqueous aldehyde solution is prepared by mixing formaldehyde, 1,8-dialdehyde anthracene and water in a ratio of 1 mol:(0.8-1) mol:(400-500) mL; the molar ratio of formaldehyde to sodium p-aminobenzenesulfonate is (0.6-0.7):1.

[0011] By adopting the above technical solution, using 1,8-dialdehyde anthracene to replace part of formaldehyde, introducing the hydrophobic conjugated large π bond in 1,8-dialdehyde anthracene into the water reducer; within this range, the ratio of hydrophobic groups to hydrophilic groups is moderate, enabling the amino sulfonic acid-based water reducer to form a stable adsorption layer on the surface of cement particles and improving water retention.

[0012] Preferably, in the step S1, the temperature for the first temperature rise is 65-75 °C, the dropping time is 1-3 h; the temperature for the second temperature rise and reaction is 85-95 °C, and the time for the second temperature rise and reaction is 4-6 h.

[0013] By adopting the above technical solution, within the temperature and time of this reaction, it is possible to obtain a sulfamic acid-based water reducer with good performance while ensuring the reaction efficiency.

[0014] Preferably, in the step S2, the dosage of amide-modified sodium lignosulfonate accounts for 10%-15% of the mass of the first substance; the reaction temperature is 90-95 °C, and the reaction time is 1-3 h.

[0015] By adopting the above technical solution, within this range of the dosage of amide-modified sodium lignosulfonate, it can better balance various properties of the sulfamic acid-based water reducer such as the dispersibility and water retention of cement particles; if the dosage of amide-modified sodium lignosulfonate is too small, it is likely to cause a decrease in the dispersibility of cement particles; if the dosage is too large, it is likely to cause the molecular structure of the sulfamic acid-based water reducer to be too complex, the intermolecular interaction to increase, and the dispersibility of the water reducer for cement particles to become poor.

[0016] Preferably, in the step S2, the preparation method of amide-modified sodium lignosulfonate includes the following steps: (1) Mix sodium lignosulfonate, hydrogen peroxide and water evenly, adjust the pH to 3-4, raise the temperature for reaction, centrifuge, impregnate, precipitate, wash and dry to obtain oxidized sodium lignosulfonate; (2) Under a nitrogen atmosphere, mix oxidized sodium lignosulfonate, sodium persulfate and water evenly, raise the temperature once, dropwise add an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid, raise the temperature for reaction a second time, impregnate, precipitate, wash and dry to obtain amide-modified sodium lignosulfonate.

[0017] By adopting the above technical solution, the number of reactive sites of oxidized sodium lignosulfonate increases, and it can better undergo a polymerization reaction with 2-acrylamido-2-methylpropanesulfonic acid, improving the performance of the water reducer.

[0018] Preferably, in the step (1), the mass ratio of sodium lignosulfonate to hydrogen peroxide is 1∶(0.1-0.15); the temperature for the temperature-raising reaction is 65-75 °C, and the time for the temperature-raising reaction is 4-5 h.

[0019] By adopting the above technical solution, under this ratio and reaction conditions, sodium lignosulfonate can be moderately oxidized without overly damaging the structure of sodium lignosulfonate.

[0020] Preferably, in the step (2), the mass ratio of sodium lignosulfonate, sodium persulfate and 2-acrylamido-2-methylpropanesulfonic acid is 1∶(0.02-0.05)∶(0.3-0.7); the mass fraction of the 2-acrylamido-2-methylpropanesulfonic acid aqueous solution is 20%-25%; the temperature for the first temperature rise is 60-65°C; the dropping time is 2-2.5 h; the temperature for the second temperature rise reaction is 70-80°C, and the time for the second temperature rise reaction is 3-4 h.

[0021] By adopting the above technical solution, after the modification of sodium lignosulfonate with 2-acrylamido-2-methylpropanesulfonic acid, the molecular structure of sodium lignosulfonate is optimized, the binding ability of sodium lignosulfonate with water molecules is increased, the free movement of water is reduced, and the water retention of concrete is improved; the introduction of sulfonic acid groups and amide groups can improve the adsorption effect of the water reducer on the surface of cement particles, making the adsorption of sodium lignosulfonate on the surface of cement particles more uniform and stable, effectively preventing the agglomeration of cement particles, improving the fluidity of concrete, and reducing the slump loss of concrete.

[0022] Preferably, in the step S3, the mass ratio of nano-silica to the second substance is (0.05-0.1)∶1; the mass fraction of the nano-silica suspension is 15%-20%.

[0023] By adopting the above technical solution, the presence of nano-silica can optimize the steric hindrance effect of the amino sulfonic acid-based water reducer molecules, adjust the adsorption state of the amino sulfonic acid-based water reducer on the surface of cement particles, and optimize the dispersion effect.

[0024] Preferably, in the step S3, the reaction temperature is 60-65°C, and the reaction time is 3-4 h.

[0025] In summary, the beneficial effects of the present invention are as follows: (1) In the present invention, amide-modified sodium lignosulfonate and nano-silica are introduced into the water reducer. The prepared amino sulfonic acid-based water reducer has a hydrophobic main chain containing groups such as phenyl, and is connected with various hydrophilic groups such as -SO3Na, -OH, -NH2 and -CONH. The synergistic effect of various groups makes the water reducer have good water retention performance, which can effectively reduce the bleeding phenomenon in concrete and improve the durability of concrete; (2) The present invention uses 4-(methylsulfonyl)phenol to replace part of phenol, and 1,8-dialdehyde anthracene to replace part of formaldehyde, introducing appropriate hydrophobic groups and hydrophilic groups into the molecular chain of the water reducer, so that the water reducer can form a stable adsorption layer on the surface of cement particles and improve the water retention; (3) The present invention uses 2-acrylamido-2-methylpropanesulfonic acid to modify sodium lignosulfonate. The introduction of sulfonic acid groups in the 2-acrylamido-2-methylpropanesulfonic acid molecule increases the binding ability of sodium lignosulfonate to water molecules, enabling it to adsorb more water molecules, reducing the free movement of water, thereby improving the water retention of concrete and avoiding bleeding and segregation phenomena in concrete. (4) The present invention introduces nano-silica into the water reducing agent, increasing the electrostatic repulsion and steric hindrance effect between cement particles, and improving the water reducing rate; the silanol groups on its surface can react with calcium ions in cement particles, etc., making the cement particles more evenly dispersed in the slurry, effectively preventing the agglomeration of cement particles, and improving fluidity. Description of the Drawings

[0026] Figure 1 It is the infrared spectrum of the amino sulfonic acid-based water reducing agent prepared in Example 1 of the present invention. Detailed Embodiments

[0027] The technical solutions of the present invention will be elaborated in detail below with reference to several representative embodiments of the present invention.

[0028] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are all conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples and comparative examples can all be obtained from commercial channels.

[0029] Example 1 A preparation method of an amino sulfonic acid-based water reducing agent in this example is as follows: S1: Add 17.22 g of 4-(methylsulfonyl)phenol, 8.47 g of phenol, 19.52 g of sodium p-aminobenzenesulfonate and 300 mL of water to a three-necked flask, stir for 20 min, adjust the pH to 11, heat up to 70 °C for the first time, dropwise add an aldehyde aqueous solution, the dropping time is 3 h, heat up to 95 °C for the second time and react for 5 h, and then perform spray drying to obtain the first substance; the aldehyde aqueous solution is prepared by stirring 1.8 g of formaldehyde, 12.65 g of 1,8-dialdehyde anthracene and 28.8 mL of water for 15 min; S2: Add 2.6 g of amide-modified sodium lignosulfonate, 20 g of the first substance and 80 mL of water to a three-necked flask, stir for 30 min, adjust the pH to 10, heat up to 92 °C and react for 2 h, and then perform spray drying to obtain the second substance; S3: Add 30 g of the second substance and 75 mL of water to a three-necked flask, stir for 30 min, dropwise add 20 g of a 15% nano-silica suspension, heat up to 60 °C and react for 3 h to obtain the amino sulfonic acid-based water reducing agent; the infrared spectrum of the amino sulfonic acid-based water reducing agent is shown in Figure 1 .

[0030] In the infrared spectrum of the amino sulfonic acid-based water reducer, the peak at 3435 cm -1 is the superposition of the stretching vibration peaks of amino, amide and hydroxyl groups; the peak at 2926 cm -1 is the absorption peak of C-H stretching vibration; the peak at 1676 cm -1 is the absorption peak of C=O stretching vibration; the peaks at 1600 cm -1 , 1516 cm -1 and 1465 cm -1 and the nearby peaks are the absorption peaks of the stretching vibration of the carbon-carbon double bond in the benzene ring conjugate system; the peak at 1448 cm -1 is the absorption peak of N-H; the peaks at 1338 cm -1 and 1120 cm -1 are the absorption peaks of the stretching vibration of the sulfonic acid group, and the peak at 1042 cm -1 is the absorption peak of the stretching vibration of C-O-C; the peak at 806 cm -1 is the absorption peak of the stretching vibration of Si-O-Si; In summary, the above infrared spectrum contains the absorption peaks of groups such as benzene ring, amino group, hydroxyl group, amide group, sulfonic acid group, ether bond and silicon-oxygen bond, which proves the successful synthesis of the amino sulfonic acid-based water reducer.

[0031] The preparation method of the amide-modified sodium lignosulfonate in this example is as follows: (1) Add 53.45 g of sodium lignosulfonate, 8 g of hydrogen peroxide and 100 mL of water to a three-necked flask, stir for 20 min, adjust the pH to 3, heat up to 65 °C and react for 4 h, centrifuge, impregnate with absolute ethanol, precipitate, wash with water, and place in a vacuum drying oven at 50 °C for 8 h to obtain oxidized sodium lignosulfonate; (2) Under a nitrogen atmosphere, add 50 g of oxidized sodium lignosulfonate, 1 g of sodium persulfate and 100 mL of water to a three-necked flask, stir for 20 min, heat up to 65 °C for the first time, dropwise add 140 g of a 25% aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid, and the dropping time is 2.5 h. Heat up to 70 °C for the second time and react for 4 h, impregnate with absolute ethanol, precipitate, wash with water, and place in a vacuum drying oven at 50 °C for 12 h to obtain amide-modified sodium lignosulfonate.

[0032] Example 2 The preparation method of an amino sulfonic acid-based water reducer in this example is as follows: S1: Add 18.94 g of 4-(methylsulfonyl)phenol, 9.4 g of phenol, 19.52 g of sodium p-aminobenzenesulfonate and 300 mL of water into a three-necked flask, stir for 20 min, adjust the pH to 9, heat up to 65 °C at one time, dropwise add an aldehyde aqueous solution, the dropping time is 1 h, heat up to 85 °C for the second time and react for 5 h, then spray dry to obtain the first substance; the aldehyde aqueous solution is prepared by stirring 2.1 g of formaldehyde, 13.12 g of 1,8-dialdehyde anthracene and 28 mL of water for 15 min; S2: Add 3 g of amide-modified lignosulfonate, 20 g of the first substance and 80 mL of water into a three-necked flask, stir for 30 min, adjust the pH to 11, heat up to 90 °C and react for 2 h, then spray dry to obtain the second substance; S3: Add 30 g of the second substance and 75 mL of water into a three-necked flask, stir for 30 min, dropwise add 7.5 g of a 20% nano-silica suspension, heat up to 65 °C and react for 4 h to obtain an amino sulfonic acid-based water reducer.

[0033] The preparation method of the amide-modified lignosulfonate in this example is as follows: (1) Add 53.45 g of lignosulfonate, 5.35 g of hydrogen peroxide and 100 mL of water into a three-necked flask, stir for 20 min, adjust the pH to 3, heat up to 75 °C and react for 5 h, centrifuge, impregnate with absolute ethanol, precipitate, wash with water, and place in a vacuum drying oven at 50 °C for 8 h to obtain oxidized lignosulfonate; (2) Under a nitrogen atmosphere, add 50 g of oxidized lignosulfonate, 2.5 g of sodium persulfate and 100 mL of water into a three-necked flask, stir for 20 min, heat up to 60 °C at one time, dropwise add 125 g of a 20% 2-acrylamido-2-methylpropanesulfonic acid aqueous solution, the dropping time is 2 h, heat up to 75 °C for the second time and react for 3 h, impregnate with absolute ethanol, precipitate, wash with water, and place in a vacuum drying oven at 50 °C for 12 h to obtain amide-modified lignosulfonate.

[0034] Example 3 The preparation method of an amino sulfonic acid-based water reducer in this example is as follows: S1: Add 20.65 g of 4-(methylsulfonyl)phenol, 7.53 g of phenol, 19.52 g of sodium p-aminobenzenesulfonate and 300 mL of water into a three-necked flask, stir for 20 min, adjust the pH to 10, heat up to 75 °C at one time, dropwise add an aldehyde aqueous solution, the dropping time is 3 h, heat up to 90 °C for the second time and react for 4 h, then spray dry to obtain the first substance; the aldehyde aqueous solution is prepared by stirring 1.95 g of formaldehyde, 15.23 g of 1,8-dialdehyde anthracene and 32.5 mL of water for 15 min; S2: Add 2.4 g of amide-modified sodium lignosulfonate, 20 g of the first substance, and 80 mL of water to a three-necked flask, stir for 30 min, adjust the pH to 9, raise the temperature to 95 °C, react for 1 h, and perform spray drying to obtain the second substance; S3: Add 30 g of the second substance and 75 mL of water to a three-necked flask, stir for 30 min, dropwise add 10.5 g of a 17% nano-silica suspension, raise the temperature to 60 °C, and react for 4 h to obtain an amino sulfonic acid-based water reducer.

[0035] The preparation method of the amide-modified sodium lignosulfonate in this example is as follows: (1) Add 53.45 g of sodium lignosulfonate, 6.4 g of hydrogen peroxide, and 100 mL of water to a three-necked flask, stir for 20 min, adjust the pH to 4, raise the temperature to 70 °C, react for 4 h, perform centrifugation, impregnate with absolute ethanol, precipitate, wash with water, and dry in a vacuum drying oven at 50 °C for 8 h to obtain oxidized sodium lignosulfonate; (2) Under a nitrogen atmosphere, add 50 g of oxidized sodium lignosulfonate, 1.5 g of sodium persulfate, and 100 mL of water to a three-necked flask, stir for 20 min, raise the temperature to 60 °C for the first time, dropwise add 68 g of a 22% 2-acrylamido-2-methylpropanesulfonic acid aqueous solution over 2.5 h, raise the temperature to 80 °C for the second time, react for 4 h, impregnate with absolute ethanol, precipitate, wash with water, and dry in a vacuum drying oven at 50 °C for 12 h to obtain amide-modified sodium lignosulfonate.

[0036] Example 4 The preparation method of an amino sulfonic acid-based water reducer in this example is as follows: S1: Add 17.22 g of 4-(methylsulfonyl)phenol, 9.4 g of phenol, 19.52 g of sodium p-aminobenzenesulfonate, and 300 mL of water to a three-necked flask, stir for 20 min, adjust the pH to 11, raise the temperature to 70 °C for the first time, dropwise add an aldehyde aqueous solution over 2 h, raise the temperature to 90 °C for the second time, react for 6 h, and perform spray drying to obtain the first substance; the aldehyde aqueous solution is prepared by stirring 2.1 g of formaldehyde, 14.76 g of 1,8-dialdehyde anthracene, and 31.5 mL of water for 15 min; S2: Add 2 g of amide-modified sodium lignosulfonate, 20 g of the first substance, and 80 mL of water to a three-necked flask, stir for 30 min, adjust the pH to 9, raise the temperature to 95 °C, react for 3 h, and perform spray drying to obtain the second substance; S3: Add 30 g of the second substance and 75 mL of water to a three-necked flask, stir for 30 min, dropwise add 16 g of a 15% nano-silica suspension, raise the temperature to 63 °C, and react for 3 h to obtain an amino sulfonic acid-based water reducer.

[0037] The preparation method of the amide-modified sodium lignosulfonate in this embodiment is as follows: (1) Add 53.45 g of sodium lignosulfonate, 6.95 g of hydrogen peroxide and 100 mL of water into a three-necked flask, stir for 20 min, adjust the pH to 4, heat up to 68 °C and react for 5 h, centrifuge, impregnate with absolute ethanol, precipitate, wash with water, and place in a vacuum drying oven at 50 °C for drying for 8 h to obtain oxidized sodium lignosulfonate; (2) Under a nitrogen atmosphere, add 50 g of oxidized sodium lignosulfonate, 1 g of sodium persulfate and 100 mL of water into a three-necked flask, stir for 20 min, heat up to 65 °C for the first time, dropwise add 113 g of an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid with a mass fraction of 22%, and the dropping time is 2 h. Heat up to 75 °C for the second time and react for 3 h, impregnate with absolute ethanol, precipitate, wash with water, and place in a vacuum drying oven at 50 °C for drying for 12 h to obtain amide-modified sodium lignosulfonate.

[0038] Comparative Example 1 The difference from Example 1 is that in this comparative example, 4-(methylsulfonyl)phenol is replaced with an equimolar amount of phenol in step S1, and the rest is the same as in Example 1.

[0039] Comparative Example 2 The difference from Example 1 is that in this comparative example, 1,8-dialdehyde anthracene is replaced with an equimolar amount of formaldehyde in step S1, and the rest is the same as in Example 1.

[0040] Comparative Example 3 The difference from Example 1 is that in this comparative example, the amount of amide-modified sodium lignosulfonate in step S2 accounts for 55% of the mass of the first substance, and the rest is the same as in Example 1.

[0041] Comparative Example 4 The difference from Example 1 is that in the preparation method of amide-modified sodium lignosulfonate in this comparative example, the mass ratio of oxidized sodium lignosulfonate to 2-acrylamido-2-methylpropanesulfonic acid is 1:2, and the rest is the same as in Example 1.

[0042] Comparative Example 5 The difference from Example 1 is that in this comparative example, the preparation in step S2 of Example 1 is not carried out, and the rest is the same as in Example 1; the preparation method of the amino sulfonate-based water reducer in this comparative example is as follows: S1: Add 17.22 g of 4-(methylsulfonyl)phenol, 8.47 g of phenol, 19.52 g of sodium p-aminobenzenesulfonate and 300 mL of water into a three-necked flask, stir for 20 min, adjust the pH to 11, heat up to 70 °C at one time, dropwise add an aqueous aldehyde solution, the dropping time is 3 h, heat up to 95 °C for the second time and react for 5 h, then perform spray drying to obtain the first substance; the aqueous aldehyde solution is prepared by stirring 1.8 g of formaldehyde, 12.65 g of 1,8-dialdehyde anthracene and 28.8 mL of water for 15 min; S2: Add 30 g of the first substance and 75 mL of water into a three-necked flask, stir for 30 min, dropwise add 20 g of a 15% nano-silica suspension, heat up to 60 °C and react for 3 h to obtain an amino sulfonic acid-based water reducer.

[0043] Comparative Example 6 The difference from Example 1 is that in step S3 of this comparative example, the mass ratio of nano-silica to the second substance is 0.5:1, and the rest are the same as in Example 1.

[0044] Comparative Example 7 The difference from Example 1 is that this comparative example does not perform the preparation in step S3 of Example 1, and the rest are the same as in Example 1; the preparation method of the amino sulfonic acid-based water reducer in this comparative example is as follows: S1: Add 17.22 g of 4-(methylsulfonyl)phenol, 8.47 g of phenol, 19.52 g of sodium p-aminobenzenesulfonate and 300 mL of water into a three-necked flask, stir for 20 min, adjust the pH to 11, heat up to 70 °C at one time, dropwise add an aqueous aldehyde solution, the dropping time is 3 h, heat up to 95 °C for the second time and react for 5 h, then perform spray drying to obtain the first substance; the aqueous aldehyde solution is prepared by stirring 1.8 g of formaldehyde, 12.65 g of 1,8-dialdehyde anthracene and 28.8 mL of water for 15 min; S2: Add 2.6 g of amide-modified lignosulfonate, 20 g of the first substance and 80 mL of water into a three-necked flask, stir for 30 min, adjust the pH to 10, heat up to 92 °C and react for 2 h to obtain an amino sulfonic acid-based water reducer.

[0045] Comparative Example 8 The preparation method of the amino sulfonic acid-based water reducer in this comparative example is as follows: Add 17.88 g of phenol, 19.52 g of sodium p-aminobenzenesulfonate and 300 mL of water into a three-necked flask, stir for 20 min, adjust the pH to 11, heat up to 70 °C at one time, dropwise add an aqueous aldehyde solution, the dropping time is 3 h, heat up to 95 °C and react for 5 h to obtain an amino sulfonic acid-based water reducer; the aqueous aldehyde solution is prepared by stirring 3.42 g of formaldehyde and 28.8 mL of water for 15 min.

[0046] Relevant performance tests The amino sulfonate superplasticizers prepared in Examples 1 - 4 and Comparative Examples 1 - 8 were subjected to relevant performance tests, and the test results are shown in Tables 1 and 2.

[0047] Cement paste fluidity: Tested in accordance with GB / T 8077 - 2000 "Test Methods for Homogeneity of Concrete Admixtures".

[0048] Concrete application performance test: Cement: P.O42.5 cement was used; Sand: Medium sand with a fineness modulus of 2.6; Stone: Crushed stone with a particle size of 5 - 40 mm (two - stage grading, small stones of 5 - 20 mm accounted for 40%, large stones of 21 - 40 mm accounted for 60%); The concrete mix ratio was: 3.3 kg of cement, 7.1 kg of sand, 7.05 kg of large stones, 4.6 kg of small stones. Adjust the dosage of the superplasticizer to keep the concrete slump at 7 - 9 cm; Tested in accordance with GB / T8076 - 2008 "Concrete Admixtures".

[0049] Table 1 Cement paste fluidity

[0050] Table 2 Concrete performance

[0051] From the comparison between Comparative Examples 1, 2 and Example 1, it can be seen that the introduction of 4 - (methylsulfonyl)phenol and 1,8 - dialdehyde anthracene can balance the hydrophilic and hydrophobic groups in the amino sulfonate superplasticizer molecule, improving the water retention of the amino sulfonate superplasticizer.

[0052] From the comparison between Comparative Examples 3, 5 and Example 1, it can be seen that the introduction of amide - modified lignosulfonate sodium can improve the performance such as water retention of concrete, but excessive dosage is likely to make the molecular structure of the amino sulfonate superplasticizer disordered, damaging the molecular structure and resulting in a decrease in the performance of the amino sulfonate superplasticizer.

[0053] From the comparison between Comparative Example 4 and Example 1, it can be seen that when 2 - acrylamido - 2 - methylpropanesulfonic acid is in excess, it may lead to excessive branching or cross - linking of the molecular chain, making the adsorption form of the superplasticizer molecule on the surface of cement particles complex and unstable, unable to form a tight and ordered adsorption layer, and reducing the water - reducing rate and overall water retention of the concrete.

[0054] From the comparison between Comparative Examples 6, 7 and Example 1, it can be seen that nano - silica has a high specific surface area and surface activity, can adsorb on the surface of cement particles, enhancing the dispersion effect of the superplasticizer on cement particles; However, when the content of nano - silica is too high, it is easy to form cross - linked polymers, which is not conducive to dispersion; The introduction of nano - silica can fill the pores and micro - cracks in the concrete, making the internal structure of the concrete more dense, reducing the porosity, reducing the bleeding phenomenon of the concrete, and improving the compressive strength of the concrete.

[0055] Comparing Comparative Example 8 with Example 1, it can be seen that the concrete prepared with the sulfamic acid-based water reducer prepared by the present invention has good water retention, water reduction rate and other properties.

[0056] The above is an exemplary description of the present invention. It should be noted that without departing from the core of the present invention, any simple deformation, modification or equivalent substitution that can be made by those skilled in the art without creative labor falls within the protection scope of the present invention.

Claims

1. A preparation method of an amino sulfonic acid-based water reducing agent, characterized in that, It includes the following steps: S1: Mix 4-(methylsulfonyl)phenol, phenol, sodium p-aminobenzenesulfonate and water evenly, adjust the pH to 9 - 11, raise the temperature for the first time, dropwise add an aqueous aldehyde solution, raise the temperature for the second time and react, then dry to obtain the first substance; S2: Mix sodium amide-modified lignosulfonate, the first substance and water evenly, adjust the pH to 9 - 11 and then react, then dry to obtain the second substance; S3: Mix the second substance and water evenly, dropwise add a nano-silica suspension and react to obtain an amino sulfonic acid-based water reducer.

2. The preparation method of a sulfamic acid-based water reducer according to claim 1, characterized in that, In the step S1, the molar ratio of 4-(methylsulfonyl)phenol, phenol to sodium p-aminobenzenesulfonate is (1 - 1.2)∶(0.8 - 1)∶1.

3. The preparation method of an amino sulfonic acid-based water reducer according to claim 1, characterized in that, In the step S1, the aqueous aldehyde solution is prepared by mixing formaldehyde, 1,8-dialdehyde anthracene and water in a ratio of 1 mol∶(0.8 - 1) mol∶(400 - 500) mL; the molar ratio of formaldehyde to sodium p-aminobenzenesulfonate is (0.6 - 0.7)∶1.

4. The preparation method of a sulfamic acid-based water reducer according to claim 1, characterized in that In the step S1, the temperature for the first temperature rise is 65 - 75 °C, the dropping time is 1 - 3 h; the temperature for the second temperature rise and reaction is 85 - 95 °C, and the reaction time for the second temperature rise is 4 - 6 h.

5. The preparation method of a sulfamic acid-based water reducing agent according to claim 1, characterized in that, In the step S2, the dosage of sodium amide-modified lignosulfonate accounts for 10% - 15% of the mass of the first substance; the reaction temperature is 90 - 95 °C, and the reaction time is 1 - 3 h.

6. The preparation method of an amino sulfonic acid-based water reducer according to claim 1, characterized in that, In the step S2, the preparation method of sodium amide-modified lignosulfonate includes the following steps: (1) Mix lignosulfonate, hydrogen peroxide and water evenly, adjust the pH to 3 - 4, raise the temperature and react, centrifuge, impregnate, precipitate, wash and dry to obtain oxidized lignosulfonate; (2) Under a nitrogen atmosphere, mix oxidized lignosulfonate, sodium persulfate and water evenly, raise the temperature for the first time, dropwise add an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid, raise the temperature for the second time and react, impregnate, precipitate, wash and dry to obtain sodium amide-modified lignosulfonate.

7. The preparation method of a sulfamic acid-based water reducing agent according to claim 6, characterized in that, In the step (1), the mass ratio of lignosulfonate to hydrogen peroxide is 1∶(0.1 - 0.15); the temperature for the temperature rise and reaction is 65 - 75 °C, and the reaction time for the temperature rise is 4 - 5 h.

8. The preparation method of a sulfamic acid-based water reducer according to claim 6, characterized in that, In the step (2), the mass ratio of oxidized lignosulfonate, sodium persulfate to 2-acrylamido-2-methylpropanesulfonic acid is 1∶(0.02 - 0.05)∶(0.3 - 0.7); the mass fraction of the aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid is 20% - 25%; the temperature for the first temperature rise is 60 - 65 °C; the dropping time is 2 - 2.5 h; the temperature for the second temperature rise and reaction is 70 - 80 °C, and the reaction time for the second temperature rise is 3 - 4 h.

9. The preparation method of a sulfamic acid-based water reducing agent according to claim 1, characterized in that, In the step S3, the mass ratio of nano-silica to the second substance is (0.05 - 0.1)∶1; the mass fraction of the nano-silica suspension is 15% - 20%.

10. The preparation method of a sulfamic acid-based water reducer according to claim 1, characterized in that, In the step S3, the reaction temperature is 60 - 65 °C, and the reaction time is 3 - 4 h.

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