A super-high dispersion water reducer and its preparation method

Abstract

A super-high dispersion water reducing agent and its preparation method. It relates to the field of concrete admixtures. It includes the following components in parts by weight: hyperbranched polyether A: 50-70 parts, modified alkylene alkenyl polyoxyethylene ether: 120-140 parts, acrylic acid: 17.5-24.3 parts, sodium methallylsulfonate: 10.0-15.0 parts, initiator: 1-6 parts, chain transfer agent: 0.7-4 parts, reducing agent: 0.23-2 parts, water: 180-300 parts. The modified alkylene alkenyl polyoxyethylene ether is one or more of ethylene glycol mono vinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyethylene glycol ether. The initiator is one or more of ammonium persulfate, potassium persulfate or hydrogen peroxide. The chain transfer agent is one or more of isopropyl alcohol, sodium hypophosphite or sodium formate. The reducing agent is one or more of vitamin C, sodium bisulfite or ferrous sulfate. The present invention fundamentally improves the performance of PCE. By reducing the cement dosage and water consumption.

Description

Technical Field

[0001] The present invention relates to the field of concrete admixtures, and relates to an ultra-high dispersion water reducing agent and a preparation method thereof. Background Art

[0002] As a representative of the third-generation high-performance water reducing agent, polycarboxylate-based water reducing agent (PCE) has the characteristics of low dosage, high water reduction rate, significant strengthening effect, strong slump retention ability, good adaptability to cement, green environmental protection, etc., and is highly favored in the concrete admixture industry. The molecular structure of PCE is designable, and products with different functional characteristics can be prepared according to the use needs, occupying more than about 80% of the domestic concrete water reducing agent market, and has become an important means to promote the development of concrete technology. The solution to the existing problems of UHPC concrete (i.e., ultra-high performance concrete) is inseparable from the improvement of PCE performance.

[0003] The key factor for the improvement of PCE performance lies in the molecular structure of its main raw material - polyether macromonomer. At present, the mainstream products of polyether macromonomers in China are isobutenyl polyethylene glycol ether (HPEG), isopentenyl polyethylene glycol ether (TPEG), as well as ethylene glycol mono vinyl polyethylene glycol ether (VEPEG, 2+2 or 2+2+2 structure) and 4-hydroxybutyl vinyl polyethylene glycol ether (VBPEG, 2+4 structure) newly introduced in the past two years.

[0004] The water reduction rate of the conventional structure PCE prepared with the existing polyether macromonomer is usually 25% - 35%, and the saturation dosage in concrete is usually 1.0% - 2.0%. Therefore, the ultimate water reduction rate is difficult to exceed 50%. A large number of practices have confirmed that a slight decrease in the water-binder ratio of UHPC will lead to a significant decrease in fluidity and a significant increase in viscosity. At this time, even if the dosage of PCE is doubled, the workability cannot be improved, resulting in a very limited space for reducing the water-binder ratio of UHPC, thus greatly limiting the improvement of UHPC strength. Therefore, it must be achieved by using PCE with a higher water reduction rate and higher dispersion.

[0005] As the main raw material for synthesizing PCE, polyether macromonomer is the most critical factor affecting PCE performance. However, using the existing polyether, only by changing the main chain structure and optimizing the synthesis process, the room for improving PCE performance is very limited.

[0006] Patent CN105601827A discloses a preparation method of a PCE with ultra-high water-reducing performance, which includes polymerizing an unsaturated carboxylic acid monomer A, an unsaturated phosphoric acid monomer B, a UV-active special monomer C, and a co-initiator monomer D in a toluene solution using an initiator E by thermal initiation to obtain a UV-active macromolecule F; dissolving the prepared solid active macromolecule F in deionized water, and under the irradiation of ultraviolet light, slowly dropping N-vinylpyrrolidone (N-VP) and monomer A to carry out a graft polymerization reaction to obtain the final water-reducing agent molecule.

[0007] Patent CN112480330A discloses an application of a novel polyether macromonomer EPEG in the synthesis of a viscosity-reducing water-reducing agent at low temperature. While having the viscosity-reducing performance, this water-reducing agent also has water-reducing, slump retention, and anti-clay properties, solving the problems of high viscosity, poor workability, rapid loss, and difficult high-rise concrete pumping caused by a large amount of clay in current concrete raw materials.

[0008] CN109608593A discloses a preparation method of a novel polyether room-temperature synthesized water-reducing polycarboxylate water-reducing agent. Using the novel polyether EPEG as a macromonomer, it has high reaction activity, a simple preparation process, short required time, and low energy consumption, and can be synthesized at room temperature. The synthesized product has the advantages of low dosage, high water-reducing rate, good slump retention performance, environmental friendliness, etc., and its performance is superior to that of similar products, having a good market prospect.

[0009] CN112876620 discloses a method for synthesizing a polycarboxylate water-reducing agent by mixing C4-6 macromonomers to obtain a high-performance water-reducing agent for concrete.

[0010] However, the water-reducing rate of the polycarboxylate water-reducing agent prepared based on the novel polyether macromonomer EPEG is limited and cannot meet the use requirements of UHPC under a low water-binder ratio. Summary of the Invention

[0011] The present invention aims at the above problems and provides an ultra-high dispersion water-reducing agent and its preparation method.

[0012] The technical solution of the present invention is: an ultra-high dispersion water-reducing agent, comprising the following components in parts by weight:

[0013] Hyperbranched polyether A: 50 - 70 parts

[0014] Modified alkylene alkenyl polyoxyethylene ether: 120 - 140 parts

[0015] Acrylic acid: 17.5 - 24.3 parts

[0016] Sodium methallylsulfonate: 10.0 - 15.0 parts

[0017] Initiator: 1 - 6 parts

[0018] Chain transfer agent: 0.7 - 4 parts

[0019] Reducing agent: 0.23 - 2 parts

[0020] Water: 180 - 300 parts.

[0021] The modified alkylene alkenyl polyoxyethylene ether is one or more of ethylene glycol mono vinyl polyethylene glycol ether and 4 - hydroxybutyl vinyl polyethylene glycol ether.

[0022] The initiator is one or more of ammonium persulfate, potassium persulfate or hydrogen peroxide.

[0023] The chain transfer agent is one or more of isopropyl alcohol, sodium hypophosphite or sodium formate.

[0024] The reducing agent is one or more of vitamin C, sodium bisulfite or ferrous sulfate.

[0025] A preparation method of a highly dispersed water - reducing agent, comprising the following steps:

[0026] S1. Preparation of hyperbranched intermediate Ⅰ (PEN): Add a catalyst to 100 - 200 parts of N, N - dihydroxyethyl - 3 - aminopropionic acid. Under nitrogen protection, heat. After N, N - dihydroxyethyl - 3 - aminopropionic acid melts, start stirring at a rotation speed of 40 - 60 rpm;

[0027] When the reaction temperature in the kettle reaches 150 °C, open the water outlet valve and collect small - molecule water with a measuring cylinder. When the water outlet becomes very slow, close the water outlet valve, open the vacuum pump to start pumping vacuum. When the vacuum degree reaches 70 Pa, set the kettle temperature to 220 °C. After a vacuum reaction time of 2 - 3 h, stop stirring, fill nitrogen to normal pressure and then discharge to obtain the hyperbranched intermediate (PEN);

[0028] The catalyst in step S1 is one or more of zinc acetate dihydrate or stannous chloride, and the added weight is 0.03 - 0.06% of the mass of N, N - dihydroxyethyl - 3 - aminopropionic acid.

[0029] S2. Preparation of hyperbranched intermediate Ⅱ (PENO): Add the catalyst and 400 - 800 parts of PEN to a reaction flask equipped with a reflux condenser, and dropwise add 10 - 20 parts of ethylene oxide; React under gentle boiling for 4 - 6 h, then cool; Filter out the catalyst, collect the product under pressure to obtain the hyperbranched intermediate Ⅱ (PENO);

[0030] The catalyst in step S2 is one or more of double - metal cyanide or potassium hydroxide, and the added weight is 0.12 - 0.15% of the reaction system (i.e., the weight of PEN).

[0031] S3. Preparation of hyperbranched polyether A: The esterification reaction of the prepared PENO and unsaturated carboxylic acid is carried out in a three-necked flask equipped with a water separator and a reflux condenser, a certain amount of water-carrying agent and catalyst are added, and the mixture is heated in a constant temperature oil bath at 140-160° C. and reacted for 5-7 hours to obtain hyperbranched polyether A.

[0032] In step S3, the PENO / unsaturated carboxylic acid molar ratio is 1.2-1.4.

[0033] In step S3, the water-carrying agent is one or more of petroleum ether, carbon tetrachloride or cyclohexane, and the weight added is 0.4-0.8% of the reaction system (i.e. the total weight of PENO and unsaturated carboxylic acid).

[0034] In step S3, the catalyst is one or more of p-toluenesulfonic acid or aminosulfonic acid, and the added weight is 0.05-0.2% of the reaction system (ie, the total weight of PENO and unsaturated carboxylic acid).

[0035] S4. Add the prepared hyperbranched polyether A and modified alkylene polyoxyethylene ether into a 1L four-necked flask, add a certain amount of ultrapure water and a magnetic stirrer to fully dissolve; weigh a certain amount of reducing agent and chain transfer agent and dissolve them in water to obtain solution A for use; weigh a certain amount of AA (i.e. acrylic acid) and MAS (i.e. sodium methyl propylene sulfonate) and dissolve them in water to obtain a mixed solution B for use; weigh a certain amount of initiator APS and add it to the four-necked flask, stir for 5-10 minutes, wait for the temperature of the oil bath to stabilize at 60°C, and then drip the two mixed solutions A and B into the macromonomer solution through a peristaltic pump, reflux at normal pressure, and stir mechanically. The dripping of solution A is completed in about 2.5 hours, and the dripping of solution B is completed in about 2 hours, and then the oil bath is heated to 75°C and kept warm for 3 hours. After the reaction is completed, adjust the pH to about 7 with a 30% by weight NaOH aqueous solution to obtain an ultra-high dispersion water reducer.

[0036] The molecular weight of the hyperbranched intermediate I (PEN) is 2000-4000.

[0037] The molecular weight of the hyperbranched intermediate II (PENO) is 4000-10000.

[0038] The molecular weight of the hyperbranched polyether A is 4000-10000.

[0039] The molecular weight of the ultra-high dispersion water reducer is 50,000-80,000.

[0040] In the process of the present invention, the performance of PCE is fundamentally improved by preparing a new polyether monomer and changing the structure of the polyether macromonomer.

[0041] When the ultra-high dispersion type PCE in the present invention is applied to cement-based materials, it can achieve ultra-high dispersion at a low water-binder ratio, promote cement hydration, make the microstructure denser, thereby improving the durability of concrete, extending the service life, and reducing environmental pollution such as carbon emissions and construction waste caused by building demolition. By reducing the cement dosage and water consumption. Detailed implementation mode

[0042] The present invention will be further described below in conjunction with specific embodiments. The purpose is to illustrate the unique concept and characteristics of the present invention, and the protection scope of the present invention cannot be limited thereby. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0043] An ultra-high dispersion type water reducer comprises the following components in parts by weight:

[0044] Hyperbranched polyether A: 50-70 parts

[0045] Modified alkylene alkenyl polyoxyethylene ether: 120-140 parts

[0046] Acrylic acid: 17.5-24.3 parts

[0047] Sodium methallylsulfonate: 10.0-15.0 parts

[0048] Initiator: 1-6 parts

[0049] Chain transfer agent: 0.7-4 parts

[0050] Reducing agent: 0.23-2 parts

[0051] Water: 180-300 parts.

[0052] The present invention improves the steric hindrance by preparing a novel hyperbranched polyether monomer and changing the structure of the polyether macromonomer, thereby fundamentally enhancing the super-dispersibility of PCE and solving problems such as the high viscosity and poor dispersibility of UHPC at a low water-binder ratio.

[0053] The ultra-high dispersion type water reducer in the present invention is as follows:

[0054]

[0055] In the formula, m and n2 are integers within 1-30; n1 and y are integers within 1-10; n, p1, p2, and p3 are integers within 1-50.

[0056] The modified alkylene alkenyl polyoxyethylene ether is one or more of ethylene glycol mono vinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyethylene glycol ether.

[0057] The initiator is one or more of ammonium persulfate, potassium persulfate, or hydrogen peroxide.

[0058] The chain transfer agent is one or more of isopropyl alcohol, sodium hypophosphite or sodium formate.

[0059] The reducing agent is one or more of vitamin C, sodium bisulfite or ferrous sulfate.

[0060] A preparation method of a highly dispersive water reducing agent comprises the following steps: (1) self-condensation of N,N-dihydroxyethyl-3-aminopropionic acid to form a hyperbranched intermediate (PEN); (2) addition of ethylene oxide to PEN to obtain a hyperbranched intermediate (PENO); (3) esterification with an unsaturated carboxylic acid to introduce a double bond to obtain a hyperbranched polyether A; (4) polymerizing the obtained hyperbranched polyether A, acrylic acid, etc. as raw materials to obtain an ultra-highly dispersive water reducing agent.

[0061] The novel polyether prepared by the present invention has a special structure, namely hyperbranched polyether A. The hyperbranched polyether structure is obtained by means of molecular design. Compared with conventional polyethers, it has a larger steric hindrance and good dispersibility.

[0062] The preparation method of the present invention mainly forms amino and carboxyl groups, has strong anchoring groups, has strong adsorption performance, improves wettability and dispersibility; a hydrophobic group (ethylene oxide) is introduced into the side chain to reduce its surface tension, improve wettability, and thus reduce viscosity. At the same time, the hyperbranched side chain can, at a low water-binder ratio, improve the steric hindrance effect, increase the charge density, etc., and improve the dispersibility. In this way, both the dispersibility and the steric hindrance are improved, so as to achieve the purpose of increasing the water reducing rate and reducing the viscosity.

[0063] The present invention prepares an ultra-highly dispersive PCE with ultra-high water reducing rate, high saturation dosage and good adaptability by optimizing the molecular structure and synthesis process of PCE, so as to further reduce the water-binder ratio of UHPC and improve its mechanical properties and durability.

[0064] A large amount of polyethers and acrylic acid are used in the preparation process of the PCE of the present invention, which both belong to a link in the petrochemical industry chain. With the progress of PCE technology and the rapid development of the concrete industry, it will drive the extension of the petrochemical industry chain and promote its development in the directions of multi-fields, high added value and personalization.

[0065] Example 1:

[0066] The invention provides a method for preparing an ultra-high dispersion water reducing agent, comprising the following steps: weighing 120g of N, N-dihydroxyethyl-3-aminopropionic acid into a polymerization kettle, and adding 0.036g of a catalyst zinc acetate dihydrate. After the addition, the air in the kettle is flushed and replaced with nitrogen for more than three times to remove oxygen. Heating, stirring is started after the N, N-dihydroxyethyl-3-aminopropionic acid is melted, and the rotation speed is 40rpm. When the reaction temperature in the kettle reaches 150°C, the water outlet valve is opened and a measuring cylinder is used to collect small molecule water. When the water outlet becomes very slow, the water outlet valve can be closed, and a vacuum pump is turned on to start vacuuming. When the vacuum degree reaches 70Pa, the kettle temperature is set to 220°C, and the vacuum reaction time is 2h, the stirring is turned off, and the material is discharged after the nitrogen is filled to normal pressure to obtain PEN.

[0067] 1.5 g of double metal cyanide catalyst and 600 g of PEN were added to a reaction bottle equipped with a reflux condenser, and 10.6 g of ethylene oxide was added dropwise. After reacting for 4 hours at a slight boiling point, the mixture was cooled, the catalyst was filtered off, and the product was collected under pressure to obtain PENO.

[0068] The esterification reaction of 630g PENO and 8.6g methacrylic acid was carried out in a three-necked flask equipped with a water separator and a reflux condenser, and heated in a constant temperature oil bath. The molar ratio of PENO / methacrylic acid was 1.4, 5.0ml of petroleum ether with water, 0.4g of aminosulfonic acid as catalyst, the reaction temperature was 150°C, and the reaction time was 6h to obtain a hyperbranched polyether.

[0069] Accurately weigh 55g of hyperbranched polyether A and 125g of polyether macromonomer into a 1L four-necked flask, add a certain amount of ultrapure water and a magnetic stirrer to fully dissolve; weigh 0.87g of reducing agent sodium bisulfite and 2.37g of chain transfer agent sodium formate and dissolve them in water to obtain solution A for use; weigh 18g of AA (i.e. acrylic acid) and 11g of MAS (i.e. sodium methyl propylene sulfonate) and dissolve them in water to obtain mixed solution B for use; weigh 5.5g of initiator APS and add it to the four-necked flask, stir for 5-10min, wait until the temperature of the oil bath pot is stable at 60℃, and then drip A and B two mixed solutions into the macromonomer solution through a peristaltic pump, reflux at normal pressure, mechanically stir, drip A solution for about 2.5h, drip B solution for about 2h, and then heat the oil bath pot to 75℃ and keep it warm for 3h. After the reaction is completed, adjust the pH to about 7 with a 30% wt NaOH aqueous solution to obtain an ultra-high dispersion water reducer.

[0070] Embodiment 2:

[0071] The invention provides a method for preparing an ultra-high dispersion water reducing agent, comprising the following steps: weighing 180g of N, N-dihydroxyethyl-3-aminopropionic acid into a polymerization kettle, and adding 0.054g of a catalyst stannous chloride at the same time. After the addition, the air in the kettle is flushed and replaced with nitrogen for more than three times to remove oxygen. Heating, stirring is started after the N, N-dihydroxyethyl-3-aminopropionic acid is melted, and the speed is 50rpm. When the reaction temperature in the kettle reaches 150°C, the water outlet valve is opened and a measuring cylinder is used to collect small molecule water. When the water outlet becomes very slow, the water outlet valve can be closed, and a vacuum pump is turned on to start vacuuming. When the vacuum degree reaches 70Pa, the kettle temperature is set to 220°C, and the vacuum reaction time is 3h, the stirring is turned off, and the material is discharged after the nitrogen is filled to normal pressure to obtain PEN.

[0072] 1.5 g of double metal cyanide catalyst and 600 g of PEN were added to a reaction bottle equipped with a reflux condenser, and 10.6 g of ethylene oxide was added dropwise. After reacting for 4 hours at a slight boiling point, the mixture was cooled, the catalyst was filtered off, and the product was collected under pressure to obtain PENO.

[0073] The esterification reaction of 840g PENO and 8.6g methacrylic acid was carried out in a three-necked flask equipped with a water separator and a reflux condenser, and heated in a constant temperature oil bath. The molar ratio of PENO / methacrylic acid was 1.3, the water-carrying carbon tetrachloride was 5.7ml, the catalyst was 0.8g sulfamic acid, the reaction temperature was 150℃, and the reaction time was 7h to obtain a hyperbranched polyether.

[0074] Accurately weigh 65g of hyperbranched polyether A and 130g of polyether macromonomer into a 1L four-necked flask, add a certain amount of ultrapure water and a magnetic stirrer to fully dissolve; weigh 1.15g of reducing agent ferrous sulfate and 3.24g of chain transfer agent isopropanol and dissolve them in water to obtain solution A for use; weigh 21g of AA and 14g of MAS and dissolve them in water to obtain mixed solution B for use; weigh 3.7g of initiator APS and add it to the four-necked flask, stir for 5-10min, wait until the temperature of the oil bath pot is stable at 60℃, and then drip A and B two mixed solutions into the macromonomer solution through a peristaltic pump, reflux at normal pressure, mechanically stir, drip A solution for about 2.5h, drip B solution for about 2h, and then heat the oil bath pot to 75℃ and keep it warm for 3h. After the reaction is completed, adjust the pH to about 7 with 30% wt NaOH aqueous solution to obtain an ultra-high dispersion water reducer.

[0075] Embodiment 3:

[0076] The invention provides a method for preparing an ultra-high dispersion water reducing agent, comprising the following steps: weighing 150g of N, N-dihydroxyethyl-3-aminopropionic acid into a polymerization kettle, and adding 0.06g of a catalyst stannous chloride at the same time. After the addition, the air in the kettle is flushed and replaced with nitrogen for more than three times to remove oxygen. Heating, stirring is started after the N, N-dihydroxyethyl-3-aminopropionic acid is melted, and the rotation speed is 60rpm. When the reaction temperature in the kettle reaches 150°C, the water outlet valve is opened and a measuring cylinder is used to collect small molecule water. When the water outlet becomes very slow, the water outlet valve can be closed, and a vacuum pump is turned on to start vacuuming. When the vacuum degree reaches 70Pa, the kettle temperature is set to 220°C, and the vacuum reaction time is 2.5h, the stirring is turned off, and the material is discharged after the nitrogen is filled to normal pressure to obtain PEN.

[0077] 1.5 g of double metal cyanide catalyst and 600 g of PEN were added to a reaction bottle equipped with a reflux condenser, and 10.6 g of ethylene oxide was added dropwise. After reacting for 4 hours at a slight boiling point, the mixture was cooled, the catalyst was filtered off, and the product was collected under pressure to obtain PENO.

[0078] The esterification reaction of 680g PENO and 8.6g methacrylic acid was carried out in a three-necked flask equipped with a water separator and a reflux condenser, and heated in a constant temperature oil bath. The molar ratio of PENO / methacrylic acid was 1.2, 5.9ml of petroleum ether with water, 0.6g of p-toluenesulfonic acid as catalyst, the reaction temperature was 150°C, and the reaction time was 6h to obtain a hyperbranched polyether.

[0079] Accurately weigh 59g of hyperbranched polyether A and 128g of polyether macromonomer into a 1L four-necked flask, add a certain amount of ultrapure water and a magnetic stirrer to fully dissolve; weigh 1.69g of reducing agent vitamin C and 2.96g of chain transfer agent sodium hypophosphite and dissolve them in water to obtain solution A for use; weigh 20g of AA and 15g of MAS and dissolve them in water to obtain mixed solution B for use; weigh 2.9g of initiator APS and add it to the four-necked flask, stir for 5-10min, wait until the temperature of the oil bath pot is stable at 60℃, and then drip A and B two mixed solutions into the macromonomer solution through a peristaltic pump, reflux at normal pressure, mechanically stir, drip A solution for about 2.5h, drip B solution for about 2h, and then heat the oil bath pot to 75℃ and keep it warm for 3h. After the reaction is completed, adjust the pH to about 7 with 30% wt NaOH aqueous solution to obtain an ultra-high dispersible water reducer.

[0080] Embodiment 4:

[0081] The invention provides a method for preparing an ultra-high dispersion water reducing agent, comprising the following steps: weighing 150g of N, N-dihydroxyethyl-3-aminopropionic acid into a polymerization kettle, and adding 0.06g of a catalyst stannous chloride at the same time. After the addition, the air in the kettle is flushed and replaced with nitrogen for more than three times to remove oxygen. Heating, stirring is started after the N, N-dihydroxyethyl-3-aminopropionic acid is melted, and the rotation speed is 60rpm. When the reaction temperature in the kettle reaches 150°C, the water outlet valve is opened and a measuring cylinder is used to collect small molecule water. When the water outlet becomes very slow, the water outlet valve can be closed, and a vacuum pump is turned on to start vacuuming. When the vacuum degree reaches 70Pa, the kettle temperature is set to 220°C, and the vacuum reaction time is 2.5h, the stirring is turned off, and the material is discharged after the nitrogen is filled to normal pressure to obtain PEN.

[0082] 0.75g potassium hydroxide catalyst and 580g PEN were added to a reaction bottle equipped with a reflux condenser, and 11.6g ethylene oxide was added dropwise. After reacting for 4 hours at a slight boiling point, the mixture was cooled, the catalyst was filtered off, and the product was collected under pressure to obtain PENO.

[0083] The esterification reaction of 780g PENO and 8.6g methacrylic acid was carried out in a three-necked flask equipped with a water separator and a reflux condenser, and heated in a constant temperature oil bath. The molar ratio of PENO / methacrylic acid was 1.3, 5.5ml of cyclohexane with water, 0.3g of sulfamic acid as catalyst, the reaction temperature was 150°C, and the reaction time was 7h to obtain a hyperbranched polyether.

[0084] Accurately weigh 57g of hyperbranched polyether A and 126g of polyether macromonomer into a 1L four-necked flask, add a certain amount of ultrapure water and a magnetic stirrer to fully dissolve; weigh 0.94g of reducing agent vitamin C and 1.88g of chain transfer agent sodium hypophosphite and dissolve them in water to obtain solution A for use; weigh 19g of AA and 12g of MAS and dissolve them in water to obtain mixed solution B for use; weigh 3.1g of initiator APS and add it to the four-necked flask, stir for 5-10min, wait until the temperature of the oil bath pot is stable at 60℃, and then drip A and B two mixed solutions into the macromonomer solution through a peristaltic pump, reflux at normal pressure, mechanically stir, drip A solution for about 2.5h, drip B solution for about 2h, and then heat the oil bath pot to 75℃ and keep it warm for 3h. After the reaction is completed, adjust the pH to about 7 with 30% wt NaOH aqueous solution to obtain an ultra-high dispersion water reducer.

[0085] Comparative example: Implementation effect verification

[0086] The commercially available polycarboxylate water reducer was used as Comparative Example 1. The super-high dispersion water reducers of Examples 1-4 of the present invention and the commercially available polycarboxylate water reducer of the comparative example were tested for their compressive and flexural strengths at different ages according to GB / T50080-2016 "Standard Test Method for Properties of Ordinary Concrete Mixtures". The mix ratio of ultra-high performance concrete used in the experiment was: reference cement 850, silica fume 150, coarse sand 346, medium sand 639, fine sand 175, steel fiber 194, mixing water 180, water reducer 23.3. The results of the examples are shown in Table 1.

[0087] Table 1 Test results of ultra-high performance concrete properties of each sample

[0088]

[0089] The present invention prepares a new polyether macromonomer with unsaturated double bonds and a hyperbranched structure, significantly improving the dispersion of PCE and having a viscosity-reducing effect. The ultra-high dispersion water reducer prepared by hyperbranched polyether achieves an ultimate water reduction rate of 50%, meeting the use of UHPC under a low water-binder ratio.

[0090] Regarding the content disclosed in this case, the following points need to be explained:

[0091] (1). The attached drawings of the embodiments disclosed in this case only relate to the structures involved in the embodiments disclosed in this case. Other structures can refer to the general design;

[0092] (2). Without conflict, the embodiments disclosed in this case and the features in the embodiments can be combined with each other to obtain new embodiments;

[0093] The above is only the specific implementation manner disclosed in this case, but the protection scope of this disclosure is not limited thereto. The protection scope disclosed in this case shall be subject to the protection scope of the claims.

Claims

1. A preparation method of a super high-dispersion water reducing agent, characterized in that, The super-dispersible water reducing agent comprises the following components in parts by weight: Hyperbranched polyether A: 50~70 parts Modified alkylene polyoxyethylene ether: 120~140 parts Acrylic acid: 17.5~24.3 parts Sodium methyl methacrylate sulfonate: 10.0~15.0 parts Initiator: 1~6 parts Chain transfer agent: 0.7~4 parts Reducing agent: 0.23~2 parts Water: 180~300 parts; The preparation method comprises the following steps: S1. Preparation of hyperbranched intermediate I PEN: Add a catalyst to 100-200 parts of N, N-dihydroxyethyl-3-aminopropionic acid, heat under nitrogen protection, and start stirring after the N, N-dihydroxyethyl-3-aminopropionic acid melts, with a rotation speed of 40-60 rpm; When the reaction temperature in the kettle reaches 150°C, open the water outlet valve. When the water is slowly discharged, close the water outlet valve, turn on the vacuum pump to start vacuuming, and when the vacuum degree reaches 70Pa, set the kettle temperature to 220°C. After the vacuum reaction time is 2-3h, turn off the stirring, fill with nitrogen to normal pressure, and then discharge the material to obtain the hyperbranched intermediate I PEN; S2. Preparation of hyperbranched intermediate II PENO: Add the catalyst and 400-800 parts of PEN to a reaction bottle equipped with a reflux condenser, and dropwise add 10-20 parts of ethylene oxide; react for 4-6 hours at a slight boiling point, and cool; filter out the catalyst, collect the product under pressure, and obtain hyperbranched intermediate II PENO; S3, preparation of hyperbranched polyether A: the esterification reaction of the prepared PENO and unsaturated carboxylic acid is carried out in a three-necked flask equipped with a water separator and a reflux condenser, a water-carrying agent and a catalyst are added, and the mixture is heated in a constant temperature oil bath at 140-160° C. and reacted for 5-7 hours to obtain a hyperbranched polyether A; S4, adding the prepared hyperbranched polyether A and modified alkylene polyoxyethylene ether into a 1L four-necked flask, adding ultrapure water and a magnetic stirrer to fully dissolve, to obtain a macromonomer solution; Weigh a reducing agent and a chain transfer agent and dissolve them in water to obtain a solution A for later use; Weigh acrylic acid and sodium methacrylic acid sulfonate and dissolve them in water to obtain a mixed solution B for later use; Weigh the initiator and add it into a four-necked flask, stir for 5-10 minutes, and after the temperature of the oil bath is stabilized at 60°C, add the mixed solutions A and B to the macromonomer solution simultaneously through a peristaltic pump, reflux at normal pressure, and stir mechanically. The A solution is added in 2.5 hours, and the B solution is added in 2 hours. Then, the oil bath is heated to 75°C and kept warm for 3 hours. After the reaction is completed, adjust the pH to 7 with a 30wt% NaOH aqueous solution to obtain an ultra-high dispersion water reducer.

2. The preparation method of a super-high dispersion water reducing agent according to claim 1, wherein: The modified alkylene polyoxyethylene ether is one or more of ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyethylene glycol ether.

3. The preparation method of a super-high dispersion water reducing agent according to claim 1, wherein: The initiator is one or more of ammonium persulfate, potassium persulfate or hydrogen peroxide.

4. The preparation method of a super-high dispersion water reducing agent according to claim 1, characterized in that: The chain transfer agent is one or more of isopropyl alcohol, sodium hypophosphite or sodium formate.

5. The preparation method of a super-high dispersion water reducing agent according to claim 1, characterized in that: The reducing agent is one or more of vitamin C, sodium bisulfite or ferrous sulfate.

6. The preparation method of a super-high dispersion water reducing agent according to claim 1, characterized in that, The catalyst in step S1 is one or more of zinc acetate dihydrate or stannous chloride, and the added weight is 0.03-0.06% of the mass of N,N-dihydroxyethyl-3-aminopropionic acid.

7. The preparation method of a super-high dispersion water reducer according to claim 1, characterized in that the catalyst in step S2 is one or more of double metal cyanide or potassium hydroxide, and the added weight is 0.12-0.15% of the reaction system.

8. The preparation method of a super-high dispersion water reducer according to claim 1, characterized in that in step S3, the molar ratio of PEN0 / unsaturated carboxylic acid is 1.2-1.4; the water-carrying agent is one or more of petroleum ether, carbon tetrachloride or cyclohexane, and the added weight is 0.4-0.8% of the reaction system; the catalyst is one or more of p-toluenesulfonic acid or sulfamic acid, and the added weight is 0.05-0.2% of the reaction system.

9. The preparation method of a super-high dispersion water reducer according to claim 1, characterized in that the molecular weight of the hyperbranched intermediate I is 2000-4000; the molecular weight of the hyperbranched intermediate II is 4000-10000; the molecular weight of the hyperbranched polyether A is 4000-10000; the molecular weight of the super-high dispersion water reducer is 50000-80000.

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