Preparation method of phosphonate water reducing agent and application thereof

Abstract

The application discloses a preparation method of a phosphonate water reducing agent and application thereof. The preparation method of the phosphonate water reducing agent comprises the following steps: firstly, adopting styrene and an unsaturated polyether monomer to perform bulk polymerization to obtain a polymerization product; secondly, adding a chloromethylation monomer into the polymerization product to perform chloromethylation to obtain a chloromethylation product; then, performing an amination reaction on the chloromethylation product and a polyamine monomer to obtain an amination product; and finally, performing a Mannich reaction and phosphitization on the amination product, formaldehyde and phosphorous acid to obtain the phosphonate water reducing agent. The reaction condition is simple and easy to operate, and the structure and performance of the obtained water reducing agent are stable. Since the main chain contains phosphonic acid adsorption groups, the water reducing agent has good anti-sulfate performance, is not sensitive to the composition of cement-based admixtures, has strong adaptability to cement, and has good slump retention performance. The phosphonate water reducing agent can be used alone or in combination with other water reducing agents on the market.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixture preparation, specifically a phosphonate water-reducing agent that is well adapted to cement, has low sulfate sensitivity, and good dispersibility and slump retention. Background Technology

[0002] Water-reducing agents are a class of polymer dispersants used in cementitious materials. Under the same solid content conditions, they can reduce the yield stress of the paste; or under the same yield stress conditions, they can increase the solid content of the paste. During concrete construction, the use of water-reducing agents can significantly improve its workability and mechanical properties. In the development history of water-reducing agents over the past few decades, it has gone through three stages: ordinary water-reducing agents, high-efficiency water-reducing agents, and high-performance water-reducing agents. Polycarboxylate superplasticizers, as the latest generation of water-reducing agents, are comb-shaped molecules with a carboxyl group containing negatively charged groups as the main chain and polyether as the long side chain. The long side chain polyether structure of polycarboxylate superplasticizers can provide effective steric hindrance, preventing the agglomeration of cement particles, thereby greatly improving the dispersion performance of the water-reducing agent. Due to its unique molecular structure (comb structure) and excellent application performance, it has received high attention from researchers at home and abroad, triggering a research boom in recent years. However, the compatibility between polycarboxylate superplasticizers and concrete raw materials has always been an important reason restricting the widespread use of polycarboxylate superplasticizers.

[0003] To address the compatibility issues of polycarboxylate superplasticizers with different types of cement and aggregates, engineers and researchers have conducted modification studies at the molecular structure level of superplasticizers based on research theories.

[0004] Patent CN201110310287.4 discloses a method for preparing a highly adaptable polycarboxylate superplasticizer. The method involves preparing a polycarboxylate superplasticizer via free radical copolymerization using a self-made macromonomer, butanol atactic polyether methacrylate, itaconic acid, sodium methacrylate sulfonate, and ethyl acrylate, initiated by ammonium persulfate. The innovation of this method lies in the preparation of an allyl ester macromonomer through esterification of methacrylic acid and butanol atactic polyether, followed by copolymerization with itaconic acid and ethyl acrylate to produce a polycarboxylate superplasticizer with strong adaptability to cement and silt-containing aggregates. Its advantages include: good adaptability to cement and silt-containing aggregates, low dosage, high water reduction rate, initial flowability of cement paste exceeding 290 mm (W / C = 0.29), good slump retention in concrete, readily available raw materials, a reasonable preparation process, no pollution during preparation, excellent product performance, and suitability for industrial production.

[0005] Patent CN201810245389.4 discloses a highly adaptable solid polycarboxylate superplasticizer and its bulk polymerization preparation method. This superplasticizer improves its adaptability by introducing phosphonic acid monomers. The solid polycarboxylate superplasticizer is made from the following raw materials in parts by weight: 100-150 parts of allyl polyethylene glycol (APEG) monomer with a degree of polymerization of 33; 21.6-32.3 parts of either acrylic acid or methacrylic acid; 16.5-29.6 parts of either maleic anhydride or diallyl maleate; 2.5-6.6 parts of either styrene or sodium styrene sulfonate; 7.5-9.6 parts of unsaturated phosphonate monomers; and an initiator, which accounts for 1%-3% of the total mass of all monomers. The unsaturated phosphonate monomers are 2-hydroxyethyl methacrylate phosphate or diethyl vinylphosphonate; the initiator is azobisisobutyronitrile, etc. This invention also provides a bulk polymerization preparation method for the solid polycarboxylate superplasticizer. The water-reducing agent of the present invention not only achieves high-performance water-reducing effect, but also has wide applicability. At the same time, the preparation process of the water-reducing agent is simple and environmentally friendly.

[0006] Patent CN201410366496.4 discloses a method for preparing a slow-release, highly adaptable polyester polycarboxylate superplasticizer. This method utilizes the principles of polymer structure design to synthesize a slow-release, non-ionic, mud-resistant polyester polycarboxylate superplasticizer product. This invention also discloses the slow-release, highly adaptable polyester polycarboxylate superplasticizer prepared by the method and its application in concrete. Compared with existing technologies, the polyester polycarboxylate superplasticizer of this invention has the following advantages: (1) The product's molecular structure contains ester and amide groups that are unstable in a strongly alkaline cement environment; (2) The amine cations generated by the hydrolysis of the amide groups have a sealing effect on negatively charged soil, achieving a mud-resistant effect; (3) It has a thickening effect on cement paste and delays the hydration of cement particles; (4) This product has a high water reduction rate, good slump retention over time, and high tolerance to soil; (5) This product has good adaptability to fly ash, mineral powder, stone powder, and clay.

[0007] Studies have shown that introducing phosphonic acid groups into water-reducing agents can improve their adaptability. Summary of the Invention

[0008] To address the aforementioned problems, one objective of this invention is to provide a method for preparing a phosphonate water-reducing agent, which introduces phosphonic acid groups as adsorption groups into the main chain, thereby improving its adaptability to cement, sulfate resistance, and slump retention compared to traditional polycarboxylate water-reducing agents.

[0009] Another object of the present invention is to provide a phosphonate water-reducing agent obtained by the above preparation method.

[0010] Another object of the present invention is to provide the application of the phosphonate water-reducing agent as a cement-based dispersant.

[0011] This invention provides a method for preparing a phosphonate water-reducing agent, comprising:

[0012] First, styrene and unsaturated polyether monomers are used for bulk polymerization to obtain a polymer product. Then, chloromethylated monomers are added to the polymer product for chloromethylation to obtain a chloromethylated product. After that, the chloromethylated product is subjected to an amination reaction with a polyamine monomer. The obtained amination product is then reacted with formaldehyde and phosphorous acid through the Mannich reaction and phosphorous acidation to obtain the phosphonate water-reducing agent of the present invention.

[0013] The molar ratio of the unsaturated polyether monomer to styrene is 1:1 to 1:6;

[0014] The amount of the chloromethylated monomer is 0.5-1.1 times that of styrene;

[0015] The molar ratio of the polyamine monomer to the chloromethylated monomer is 1:1 to 1.5:1;

[0016] The molar ratio of -NH in the phosphorous acid to the polyamine monomer is 0.2:1-1.1:1;

[0017] The formaldehyde content is 1-1.3 times the amount of phosphite.

[0018] The introduction of phosphonic acid groups in this invention can improve the adsorption performance of the water-reducing agent and enhance its sulfate resistance, making it more adaptable to cement and improving its slump retention.

[0019] The number-average molecular weight Mn of the unsaturated polyether monomers of the present invention is 1000-8000, and the unsaturated polyether monomers are selected from any one or more of allyl polyethylene glycol ether, isobutylene polyethylene glycol ether, isopentenyl polyethylene glycol ether, ethylene glycol monovinyl polyethylene glycol ether unsaturated polyether macromonomers.

[0020] The chloromethylated monomer described in this invention is a chloromethyl alkyl ether, specifically selected from chloromethyl methyl ether, dichloromethyl methyl ether, and ClCH2O(CH2). m CH3、(ClCH2O)2(CH2) n Any one of the following, where m and n are integers from 1 to 7.

[0021] The polyamine monomers described in this invention are selected from any one or more of ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexaethyleneheptamine;

[0022] The preparation method of the phosphonate water-reducing agent of the present invention specifically includes the following steps:

[0023] (1) Polymerization of styrene with unsaturated polyether monomer: Add unsaturated polyether monomer to a dry flask, heat until the polyether melts and start stirring, add initiator, then add a mixture of styrene and chain transfer agent dropwise, control the dropwise addition time, continue the reaction for a period of time after dropwise addition, and obtain the polymer product;

[0024] (2) Chloromethylation reaction: Chloromethylated monomers are added to the polymerization product in step (1), catalyst I is added, and chloromethylated products are obtained under certain reaction temperature and reaction time.

[0025] (3) Amination reaction: The chloromethylated product obtained in step (2) is added to the polyamine monomer and reacted at a certain temperature and time to obtain the amination product;

[0026] (4) Preparation of phosphonate water-reducing agent: Water, phosphorous acid, formaldehyde and catalyst II are added to the amination product in step (3), and the reaction is carried out at a certain temperature for a period of time. Water and sodium hydroxide are added to neutralize to pH=3-7 to obtain the phosphonate water-reducing agent with the desired structure.

[0027] The initiator in step (1) is selected from any one of potassium persulfate, benzoyl peroxide, and azobisisobutyronitrile, and the amount added is 1-3% of the total monomer mass of the reaction in step (1); the chain transfer agent is selected from any one of mercaptoethanol, mercaptoacetic acid, mercaptopropanol, and mercaptopropionic acid, and the amount added is 0.5-3% of the total monomer mass of the reaction in step (1).

[0028] The dropping time in step (1) is 2-4 hours, the reaction time is 2-5 hours, and the reaction temperature is 50-80℃.

[0029] The catalyst I mentioned in step (2) is phosphoric acid, sulfuric acid or F3CCOOH, and the amount added is 3%-10% of the total monomer mass of the reaction in step (2). The reaction temperature is 50-80℃ and the reaction time is 6-24h.

[0030] The reaction time in step (3) is 2-8 hours and the reaction temperature is 80-140℃.

[0031] Catalyst II in step (4) is a protic acid catalyst, which is sulfuric acid, phosphoric acid or p-toluenesulfonic acid, and the content of catalyst II accounts for 5%-20% of the total mass of the reaction monomers in step (4).

[0032] The temperature of all reactions in step (4) is 100-140℃, and the total reaction time is 6-24h.

[0033] According to a second aspect of the invention, a phosphonate water-reducing agent obtained by the preparation method is also provided.

[0034] According to a third aspect of the invention, the application of the phosphonate water-reducing agent as a dispersant for cement-based materials is also provided.

[0035] The phosphonate water-reducing agent obtained in this invention exhibits good adaptability to cement and admixtures, sulfate resistance, dispersibility, and slump retention as a dispersant for cement-based materials. When used, its dosage (consolidated dosage) is 1‰-5‰ of the cementitious material mass, with the specific dosage determined according to actual engineering needs. However, when the dosage is less than 1‰, its dispersibility is poor and cannot meet engineering requirements; when the dosage exceeds 5‰, the cost-effectiveness is low, and excessively high dosages can lead to segregation and bleeding.

[0036] This invention involves bulk polymerization of styrene and unsaturated polyether macromonomers to obtain a polymer product, followed by chlorination with a chloromethylated monomer and subsequent amination and phosphorylation to yield the corresponding water-reducing agent. The reaction conditions are simple and easy to operate, and the resulting water-reducing agent exhibits stable structure and properties. Due to the presence of phosphonate adsorption groups in the main chain, it possesses good sulfate resistance, is insensitive to cement-based admixtures, has strong adaptability to cement, and good slump retention. This phosphonate water-reducing agent can be used alone or in combination with other commercially available water-reducing agents. Detailed Implementation

[0037] To better understand this invention, the following embodiments further illustrate its content; however, the scope of this invention is not limited to the embodiments described below. All equivalent changes or modifications made in accordance with the spirit and essence of this invention should be covered within the protection scope of this invention.

[0038] In this embodiment of the invention, the molecular weight of the condensate was determined using a gel permeation chromatography (GPC) system from Wyatt Technology Corporation. The experimental conditions are as follows:

[0039] Gel column: Two Shodex SB806+803 columns connected in series;

[0040] Washing solution: 0.1M NaNO3 solution;

[0041] Mobile phase rate: 1.0 mL / min;

[0042] Injection: 20 μL 0.5% aqueous solution;

[0043] Detector: Shodex RI-71 differential refractometer;

[0044] Standard: Polyethylene glycol GPC standard (Sigma-Aldrich, molecular weight 1010000, 478000, 263000, 118000, 44700, 18600, 6690, 1960, 826, 232).

[0045] The cement used was Onoda 42.5RP‖, Helin 42.5RPO, Conch 42.5RPO, reference cement PI 42.5, and Zhongshan PO42.5 cement. The flowability of the cement paste was tested according to GB / T8077-2000 standard. 87g of water was added, and the paste was stirred for 3 minutes before being measured on a flat glass plate. For the cement mortar flowability, the reference cement was used with 450g of cement, 147.5g of water, and 1310g of standard sand.

[0046] Example 1

[0047] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0048] (1) Add 120g of allyl polyethylene glycol ether with molecular weight Mn=2400 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat to 60℃, melt the polyether and start stirring. Add 1.2g of azobisisobutyronitrile, and then slowly add a mixture of 15.6g of styrene and 1.2g of mercaptopropanol over 3h. Continue the reaction for 3h after the addition to obtain the polymer product.

[0049] (2) Add 12.07 g of chloromethyl methyl ether and 5 g of sulfuric acid to the polymerization product, heat to 70 °C, and react for 12 h to obtain the chloromethylated product;

[0050] (3) Add 9g of ethylenediamine to the chloromethylated product, heat to 100℃, and react for 3h to obtain the amination product;

[0051] (4) Add 100g of deionized water, 24.6g of phosphorous acid, 26.76g of 37% formaldehyde aqueous solution and 20g of sulfuric acid to the amination product, react at 120℃ for 8h, and neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S1 with a molecular weight Mn=16472.

[0052] Example 2

[0053] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0054] (1) Add 160g of allyl polyethylene glycol ether with molecular weight Mn=3200 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat to 50℃, melt the polyether and start stirring. Add 1.8g of azobisisobutyronitrile, and then slowly add a mixture of 15.6g of styrene and 0.9g of mercaptoethanol over 3h. Continue the reaction for 5h after the addition to obtain the polymer product.

[0055] (2) Add 18.75g ClCH2O(CH2)3CH3 to the polymerization product, add 19.7g sulfuric acid, heat to 50℃, and react for 24h to obtain the chloromethylated product;

[0056] (3) Add 26.1g of hexamethylenediamine to the chloromethylated product, heat to 140℃, and react for 2h to obtain the amination product;

[0057] (4) Add 100 g of deionized water, 40.59 g of phosphorous acid, 47.43 g of 37% formaldehyde aqueous solution and 20 g of sulfuric acid to the amination product, react at 130°C for 10 h, and then neutralize with water and sodium hydroxide to pH = 5.0 to obtain the desired phosphonate water-reducing agent S2 with a molecular weight Mn = 16724.

[0058] Example 3

[0059] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0060] (1) Add 100g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of Mn=8000 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat the flask to 80℃ to melt the polyether and start stirring. Add 3.23g of potassium persulfate. Then slowly add a mixture of 7.8g of styrene and 3.23g of mercaptoethanol over 2 hours. Continue the reaction for 2 hours after the addition to obtain the polymer product.

[0061] (2) Add 5.74g ClCH2O(CH2)5CH3 to the polymerization product, add 8g sulfuric acid, heat to 70℃, and react for 12h to obtain the chloromethylated product;

[0062] (3) Add 4.33g of diethylenetriamine to the chloromethylated product, heat to 80℃, and react for 8h to obtain the amination product;

[0063] (4) Add 100g of deionized water, 12.3g of phosphorous acid, 26.16g of 37% formaldehyde aqueous solution and 53.5g of p-toluenesulfonic acid to the amination product, react at 110℃ for 8h, and then neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S3 with a molecular weight Mn=18375.

[0064] Example 4

[0065] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0066] (1) Add 100g of allyl polyethylene glycol ether with molecular weight Mn=1000 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat to 70℃, melt the polyether and start stirring. Add 1.1g of azobisisobutyronitrile, and then slowly add a mixture of 10.4g of styrene and 1.0g of mercaptoacetic acid over 2.5h. Continue the reaction for 3h after the addition to obtain the polymer product.

[0067] (2) Add 8.05g of chloromethyl methyl ether and 6g of sulfuric acid to the polymerization product, heat to 80℃, and react for 6h to obtain the chloromethylated product;

[0068] (3) Add 14.6g of triethylenetetramine to the chloromethylated product, heat to 100℃, and react for 3h to obtain the amination product;

[0069] (4) Add 100g of deionized water, 41g of phosphorous acid, 40.54g of 37% formaldehyde aqueous solution and 16.13g of sulfuric acid to the amination product, react at 120℃ for 8h, and then neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S4 with a molecular weight Mn=16757.

[0070] Example 5

[0071] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0072] (1) Add 120g of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of Mn=2400 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat the flask to 60℃ to melt the polyether and start stirring. Add 1.2g of azobisisobutyronitrile. Then slowly add a mixture of 10.4g of styrene and 0.8g of mercaptopropanol over 4h. Continue the reaction for 4h after the addition to obtain the polymer product.

[0073] (2) Add 15.9g (ClCH2O)2(CH2)2 to the polymerization product, add 7g sulfuric acid, heat to 70℃, and react for 12h to obtain the chloromethylated product;

[0074] (3) Add 18.9g of tetraethylenepentamine to the chloromethylated product, heat to 110℃, and react for 4h to obtain the amination product;

[0075] (4) Add 100 g of deionized water, 24.6 g of phosphorous acid, 26.76 g of 37% formaldehyde aqueous solution and 20 g of sulfuric acid to the amination product, react at 120°C for 8 h, and neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S5 with a molecular weight Mn=21318.

[0076] Example 6

[0077] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0078] (1) Add 100g of isopentenyl polyethylene glycol ether with molecular weight Mn=4000 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat to 70℃, melt the polyether and start stirring. Add 1.2g of potassium persulfate, and then slowly add a mixture of 10.4g of styrene and 1.0g of mercaptoacetic acid over 3h. Continue the reaction for 5h after the addition to obtain the polymer product.

[0079] (2) Add 14.96g of (ClCH2O)2(CH2)4 and 6g of phosphoric acid to the polymerization product, heat to 70℃, and react for 18h to obtain the chloromethylated product.

[0080] (3) Add 19.04 g of pentaethylenehexamine to the chloromethylated product, heat to 120 °C, and react for 3 h to obtain the amination product;

[0081] (4) Add 100g of deionized water, 18.368g of phosphorous acid, 18.16g of 37% formaldehyde aqueous solution and 22g of sulfuric acid to the amination product, react at 100℃ for 12h, and then neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S6 with a molecular weight Mn=24658.

[0082] Example 7

[0083] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0084] (1) Add 100g of allyl polyethylene glycol ether with molecular weight Mn=5000 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat to 70℃, melt the polyether and start stirring. Add 1.2g of azobisisobutyronitrile. Then slowly add a mixture of 10.4g of styrene and 1.2g of mercaptopropionic acid over 3h. Continue the reaction for 3h after the addition to obtain the polymer product.

[0085] (2) Add 8.85g of chloromethyl methyl ether and 6g of phosphoric acid to the polymerization product, heat to 60℃, and react for 24h to obtain the chloromethylated product;

[0086] (3) Add 6g of ethylenediamine to the chloromethylated product, heat to 100℃, and react for 5h to obtain the amination product;

[0087] (4) Add 100 g of deionized water, 24.6 g of phosphorous acid, 26.76 g of 37% formaldehyde aqueous solution and 10 g of p-toluenesulfonic acid to the amination product, react at 110 °C for 18 h, and neutralize with water and sodium hydroxide to pH = 5.0 to obtain the desired phosphonate water-reducing agent S7 with a molecular weight Mn = 17678.

[0088] Example 8

[0089] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0090] (1) Add 120g of isopentenyl polyethylene glycol ether with a molecular weight of Mn=2400 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat the flask to 60℃ to melt the polyether and start stirring. Add 1.2g of benzoyl peroxide and then slowly add a mixture of 15.6g of styrene and 1.2g of mercaptopropanol over 3h. Continue the reaction for 3.5h after the addition to obtain the polymer product.

[0091] (2) Add 16.43g of (ClCH2O)2(CH2)7 to the polymerization product, add 6g of sulfuric acid, heat to 70℃, and react for 8h to obtain the chloromethylated product;

[0092] (3) Add 21.53g of hexaethyleneheptaamine to the chloromethylated product, heat to 90℃, and react for 7h to obtain the amination product;

[0093] (4) Add 100g of deionized water, 24.6g of phosphorous acid, 26.76g of 37% formaldehyde aqueous solution and 20g of sulfuric acid to the amination product, react at 130℃ for 8h, and neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S8 with a molecular weight Mn=16321.

[0094] Example 9

[0095] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0096] (1) Add 120g of isobutylene polyethylene glycol ether with a molecular weight of Mn=2400 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat the flask to 70℃ to melt the polyether and start stirring. Add 2.4g of azobisisobutyronitrile. Then slowly add a mixture of 15.6g of styrene and 1.2g of mercaptopropionic acid over 2 hours. Continue the reaction for 3 hours after the addition to obtain the polymer product.

[0097] (2) Add 10.88g of (ClCH2O)2(CH2)1 and 4.5g of F3CCOOH to the polymerization product, heat to 60℃, and react for 12h to obtain the chloromethylated product;

[0098] (3) Add 20.63g of polyethylene polyamine to the chloromethylated product, heat to 80℃, and react for 6h to obtain the amination product;

[0099] (4) Add 100 g of deionized water, 24.6 g of phosphorous acid, 26.76 g of 37% formaldehyde aqueous solution and 20 g of phosphoric acid to the amination product, react at 120°C for 16 h, and neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S9 with a molecular weight Mn=16854.

[0100] Example 10

[0101] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0102] (1) Add 120g of allyl polyethylene glycol ether with molecular weight Mn=2400 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat to 80℃, melt the polyether and start stirring. Add 1.2g of benzoyl peroxide, and then slowly add a mixture of 15.6g of styrene and 1.2g of mercaptopropanol over 3h. Continue the reaction for 3.5h after the addition to obtain the polymer product.

[0103] (2) Add 17.25g of dichloromethyl methyl ether and 10g of sulfuric acid to the polymerization product, heat to 70℃, and react for 12h to obtain the chloromethylated product;

[0104] (3) Add 9g of ethylenediamine to the chloromethylated product, heat to 100℃, and react for 3h to obtain the amination product;

[0105] (4) Add 100 g of deionized water, 18.45 g of phosphorous acid, 21.89 g of 37% formaldehyde aqueous solution and 20 g of sulfuric acid to the amination product, react at 100 °C for 24 h, and neutralize with water and sodium hydroxide to pH = 5.0 to obtain the desired phosphonate water-reducing agent S10 with a molecular weight Mn = 18464.

[0106] Example 11

[0107] The preparation method of the phosphonate water-reducing agent of the present invention includes:

[0108] (1) Add 160g of isobutylene polyethylene glycol ether with a molecular weight of Mn=3200 to a three-necked 500mL flask equipped with a stirring rod and a condenser. Heat the flask to 60℃ to melt the polyether and start stirring. Add 2.0g of potassium persulfate. Then slowly add a mixture of 15.6g of styrene and 1.0g of mercaptopropanol over 3h. Continue the reaction for 3h after the addition to obtain the polymer product.

[0109] (2) Add 12.07g of chloromethyl methyl ether and 8g of F3CCOOH to the polymerization product, heat to 70℃, and react for 12h to obtain the chloromethylated product;

[0110] (3) Add 9g of ethylenediamine to the chloromethylated product, heat to 100℃, and react for 3h to obtain the amination product;

[0111] (4) Add 100 g of deionized water, 36.9 g of phosphorous acid, 36.49 g of 37% formaldehyde aqueous solution and 20 g of phosphoric acid to the amination product, react at 140°C for 6 h, and then neutralize with water and sodium hydroxide to pH=5.0 to obtain the desired phosphonate water-reducing agent S11 with a molecular weight Mn=19545.

[0112] Comparative Example

[0113] A commercially available polycarboxylate superplasticizer with a molecular weight of Mn = 26133 was used as a control sample and named S12.

[0114] Application Examples

[0115] Application Example 1

[0116] Cement compatibility tests were conducted on the water-reducing agents in each embodiment and comparative example. Neat paste experiments were performed using Helin, Onoda, Benchmark, Zhongshan, and Conch Cement, respectively, to test their initial fluidity and loss over time.

[0117] Table 1 Evaluation Table of Cement Paste Flowability

[0118]

[0119]

[0120] As shown in Table 1, the phosphonate water-reducing agent prepared in this invention exhibits excellent dispersibility, high initial fluidity, good adaptability to cement, and good slump retention at a dosage of 0.10%, with minimal fluidity loss after 1 hour. Comparative Example S12 shows unstable fluidity performance in different cements, poor adaptability to cements, poor dispersibility in Onoda cement and Conch cement, and relatively poor fluidity loss over time. Evaluation of the paste performance of different cements shows that the synthesized phosphonate water-reducing agent has stronger adaptability to different cements.

[0121] Application Example 2

[0122] Sulfate resistance tests were conducted on the phosphonate water-reducing agent samples in each embodiment and comparative example. Neat mortar tests were performed using standard cement and standard sand. The sulfate resistance was investigated by adding different amounts of potassium sulfate. The water-reducing agent dosage was 0.1%. The results are shown in Table 2.

[0123] Table 2 Evaluation of Sulfate Resistance of Water-Reducing Agents

[0124]

[0125]

[0126] As shown in Table 2, all synthesized samples S1 and S4 exhibited better fluidity and fluidity retention over time than the control sample S12 in cement paste and mortar experiments with different amounts of potassium sulfate. This indicates that the synthesized phosphonate superplasticizer is not sensitive to sulfate dosage and has better sulfate resistance. This is because the phosphonate superplasticizer uses phosphonic acid groups as adsorption groups, which have stronger electronegativity and complexing ability for calcium ions compared to carboxylic acid groups. Therefore, it has stronger adsorption performance than polycarboxylic acid superplasticizers. When the sulfate content is too high, it is less affected by competitive adsorption by sulfate, thus exhibiting better sulfate resistance and stronger adaptability to cement.

Claims

1. A method for preparing a phosphonate water-reducing agent, characterized in that, include: First, bulk polymerization of styrene and unsaturated polyether monomers is carried out to obtain a polymer product. Then, chloromethylating monomers are added to the polymer product to obtain a chloromethylated product. Subsequently, the chloromethylated product is subjected to an amination reaction with a polyamine monomer. The obtained amination product is then reacted with formaldehyde and phosphorous acid through the Mannich reaction and phosphorous acidation to obtain the phosphonate water-reducing agent. The molar ratio of the unsaturated polyether monomer to styrene is 1:1 to 1:6; The amount of the chloromethylated monomer is 0.5-1.1 times that of styrene; The molar ratio of the polyamine monomer to the chloromethylated monomer is 1:1 to 1.5:1; The molar ratio of -NH in the phosphorous acid to the polyamine monomer is 0.2:1-1.1:1; The formaldehyde content is 1-1.3 times the amount of phosphite. The chloromethylated monomer is a chloromethyl alkyl ether; The preparation method of this phosphonate water-reducing agent specifically includes the following steps: (1) Polymerization of styrene and unsaturated polyether monomer: Add unsaturated polyether monomer to a dry flask, heat until the unsaturated polyether monomer melts and start stirring, add initiator, and then add a mixture of styrene and chain transfer agent dropwise, controlling the dropwise addition time, and continue the reaction for a period of time after the dropwise addition to obtain the polymer product; (2) Chloromethylation reaction: Chloromethylated monomers are added to the polymerization product in step (1), catalyst I is added, and chloromethylated products are obtained under certain reaction temperature and reaction time; (3) Amination reaction: The chloromethylated product obtained in step (2) is added to the polyamine monomer and reacted at a certain temperature and time to obtain the amination product; (4) Preparation of phosphonate water-reducing agent: Water, phosphorous acid, formaldehyde and catalyst II are added to the amination product in step (3), and the reaction is carried out at a certain temperature for a period of time. Water and sodium hydroxide are added to neutralize to pH=3-7 to obtain the phosphonate water-reducing agent with the desired structure.

2. The method for preparing a phosphonate water-reducing agent according to claim 1, characterized in that, The number-average molecular weight Mn of the unsaturated polyether monomer is 1000-8000.

3. The method for preparing a phosphonate water-reducing agent according to claim 2, characterized in that, The unsaturated polyether monomer is selected from any one or more of allyl polyethylene glycol ether, isobutylene polyethylene glycol ether, isopentenyl polyethylene glycol ether, ethylene glycol monovinyl polyethylene glycol ether, and unsaturated polyether macromonomers.

4. The method for preparing a phosphonate water-reducing agent according to claim 1, characterized in that, The chloromethyl alkyl ether is selected from chloromethyl methyl ether, dichloromethyl methyl ether, and ClCH2O(CH2). m CH3、 (ClCH2O)2(CH2) n Any one of the following, where m and n are integers from 1 to 7.

5. The method for preparing a phosphonate water-reducing agent according to claim 1, characterized in that, The polyamine monomer is selected from any one or more of ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexaethyleneheptamine.

6. The method for preparing a phosphonate water-reducing agent according to claim 1, characterized in that, The initiator mentioned in step (1) is selected from any one of potassium persulfate, benzoyl peroxide, and azobisisobutyronitrile, and the amount added is 1-3% of the total monomer mass of the reaction in step (1); The chain transfer agent is selected from any one of mercaptoethanol, mercaptoacetic acid, mercaptopropanol, and mercaptopropionic acid, and the amount added is 0.5-3% of the total monomer mass in step (1). The catalyst I mentioned in step (2) is phosphoric acid, sulfuric acid or F3CCOOH, and the amount added is 3%-10% of the total monomer mass of the reaction in step (2); Catalyst II in step (4) is a protic acid catalyst, which is sulfuric acid, phosphoric acid or p-toluenesulfonic acid. The content of catalyst II accounts for 5%-20% of the total mass of the reaction monomers in step (4).

7. The method for preparing a phosphonate water-reducing agent according to claim 1, characterized in that, The dropping time in step (1) is 2-4 hours, the reaction time is 2-5 hours, and the reaction temperature is 50-80℃; The reaction temperature in step (2) is 50-80℃, and the reaction time is 6-24h; The reaction time in step (3) is 2-8 hours, and the reaction temperature is 80-140℃; In step (4), the temperature of all reactions is 100-140℃, and the total reaction time is 6-24h.

8. A phosphonate water-reducing agent prepared by the preparation method according to any one of claims 1 to 7.

9. A method for applying a phosphonate water-reducing agent prepared by any one of claims 1 to 7, characterized in that, When the phosphonate water-reducing agent is used as a dispersant for cement-based materials, its dosage is 1‰-5‰ of the mass of the cementitious material.

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