A viscosity-reducing and sustained-release polyacrylate macromolecule and its preparation method and application

Abstract

The present invention discloses a viscosity-reducing and slow-release polyacrylate macromolecule and its preparation method and application, belonging to the technical field of concrete admixtures. The macromolecule of the present invention is prepared by emulsion polymerization of acrylic acid monomers, unsaturated polyether macromonomers, functional monomers A and functional monomers B. The present invention uses unsaturated polyether macromonomers commonly used in the preparation of commercially available polycarboxylic acid water-reducing agents as the main raw materials, which has obvious cost advantages. In addition, by optimizing and regulating the types and ratios of acrylic acid (ester) monomers and functional monomers A and B, a functional polyacrylate macromolecule is obtained. When used as a concrete water-reducing agent, it not only has good water-reducing and dispersing properties, but also has significant viscosity reduction and slow-release slump-retaining effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete admixtures, and in particular relates to a viscosity-reducing and slow-release polyacrylate macromolecule, a preparation method and an application thereof. Background Art

[0002] With the rapid development of concrete structures towards larger, more integrated, and more complex structures, the application of (ultra-)high-strength concrete is expanding in both breadth and depth. (Ultra-)high-strength concrete is typically produced using a low water-cement ratio. However, this low water-cement ratio results in high viscosity and poor fluidity in fresh concrete, which in turn creates significant challenges in transportation, pumping, and construction. Currently, three main approaches are used to reduce the viscosity of (ultra-)high-strength concrete in its industrial application: increasing the water-reducing agent dosage, selecting high-quality ultrafine aggregate, and optimizing particle size distribution. Increasing the water-reducing agent dosage not only increases production costs but can also lead to problems such as retarded setting, bleeding, segregation, and bottoming out, increasing construction difficulty and potentially causing accidents. The selection of high-quality ultrafine aggregate is limited by the regional availability and quality stability of cementitious materials. While optimizing particle size distribution can improve the viscosity and fluidity of fresh high-strength concrete to a certain extent, it cannot fundamentally address the problem.

[0003] Water reducers, especially polycarboxylate water reducers, have become one of the essential components of ultra-high performance cement-based materials due to their advantages such as low dosage, high water reduction rate, low fluidity loss, low shrinkage, and green and environmentally friendly properties. At the same time, their molecular structure is highly designable, and the high performance and functionalization of polycarboxylate water reducers can be achieved by controlling the main chain polymerization degree, side chain density, and functional group types. Therefore, using polycarboxylate water reducers to solve the problem of excessive concrete viscosity without changing the concrete mix ratio and raw material selection is a simple and cost-effective method. At present, research on improving and enhancing the viscosity reduction efficiency of polycarboxylate water reducers is mainly achieved by adjusting the hydrophilic-lipophilic (HLB) balance of polycarboxylate water reducer molecules. Among them, the applicant used a functional monomer with dual functions of reactivity and emulsification in invention patent CN202311526626.1 to obtain a series of new polyacrylate macromolecules. When used as water reducers, they not only have excellent water-reducing and dispersing properties, but also improve the universal performance of polycarboxylate water reducers and have excellent anti-mud sensitivity. Therefore, the present invention designs and prepares a functional polyacrylate macromolecule with both viscosity reduction and sustained release based on the molecular structure design of polycarboxylate water-reducing agent. Its use as a water-reducing agent mainly involves (super) high-strength concrete, building materials, waterproofing, gypsum boards and other building materials related fields. Summary of the Invention

[0004] In order to address the deficiencies of the prior art, the primary purpose of the present invention is to provide a functional polyacrylate macromolecule with both viscosity reduction and sustained release. The present invention also provides a preparation method and application of the functional polyacrylate macromolecule with both viscosity reduction and sustained release.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A viscosity-reducing and slow-release polyacrylate macromolecule is prepared by emulsion polymerization of acrylic monomers, unsaturated polyether macromonomers, functional monomers A and B.

[0007] Furthermore, the acrylic monomer is one or more of acrylic acid (AA), methacrylic acid (MAA), β-carboxyethyl acrylate (β-CEA), and monobutyl itaconate (MBA).

[0008] Furthermore, the acrylic monomer is acrylic acid (AA) and / or β-carboxyethyl acrylate (β-CEA).

[0009] Furthermore, the unsaturated polyether macromonomer is one of allyl polyethylene glycol ether (APEG), isobutylene polyethylene glycol ether (HPEG), isopentenyl polyethylene glycol ether (TPEG), and monoethylene-terminated diethylene glycol polyethylene glycol ether (GPEG), and the molecular weight of the unsaturated polyether macromonomer is 1000-10000;

[0010] Furthermore, the unsaturated polyether macromonomer is one or more of isobutylene polyethylene glycol ether (HPEG) and isopentenyl polyethylene glycol ether (TPEG), and has a molecular weight of 2400.

[0011] Furthermore, the functional monomer A is one or more of sodium vinyl sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, sodium allyloxyhydroxypropyl sulfonate, sodium allyl sulfonate, and sodium methyl allyl sulfonate.

[0012] Furthermore, the functional monomer A is one of sodium vinyl sulfonate and 2-acrylamido-2-methylpropanesulfonic acid.

[0013] Furthermore, the functional monomer B is one of tert-butyl acrylate, tert-butyl methacrylate, vinyl neononanoate (VV9), and vinyl versatate (VV10).

[0014] Furthermore, the functional monomer B is a combination of tert-butyl acrylate and versatate (VV10), with a mass ratio of 1:1.

[0015] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0016] (1) Preparation of mixed monomer pre-emulsion: Add 20.0-50.0 parts of deionized water, 1.0-5.0 parts of functional monomer A and 0.2 parts of initiator to a mixing kettle and stir to dissolve them. Then, add 0.5-0.8 parts of functional monomer B and 1.0-10.0 parts of acrylic monomer in sequence and stir vigorously for 30-60 minutes. Then, add 20.0-50.0 parts of unsaturated polyether macromonomer and stir for 20 minutes to obtain a mixed monomer pre-emulsion.

[0017] (2) Preparation of polyacrylate macromolecules: Add 10.0-30.0 parts of deionized water to the polymerization kettle, stir and heat to 70-90°C, then start to drop the mixed monomer pre-emulsion and control the dropwise addition time to 120-180min. After the dropwise addition is completed, continue to keep the temperature and react for 120min, then cool to 30-40°C, and adjust the pH value to 7-8 with ammonia water to obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0018] Furthermore, the initiator in step (2) is one or more of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0019] Furthermore, the initiator in step (2) is one of ammonium persulfate and potassium persulfate.

[0020] The invention discloses an application of a viscosity-reducing and slow-release polyacrylate macromolecule, which is used as a water reducer in technical fields related to building materials such as (super) high-strength concrete, waterproofing and gypsum boards.

[0021] Beneficial effects:

[0022] (1) The present invention first utilizes the sulfonic acid functional group in the structure of functional monomer A, which has a significant emulsifying function, to effectively achieve the emulsification and solubilization of the hydrophobic functional monomer B in the system, and obtain a uniform and stable mixed monomer pre-emulsion; secondly, the unsaturated double bond in the molecular structure of functional monomer A can also undergo emulsion polymerization with acrylic acid (ester) monomers and unsaturated polyether macromonomers, thereby obtaining a functional polyacrylate macromolecule, which not only has a molecular structure similar to that of traditional polycarboxylic acid water reducers, but also the electrostatic effect of the carboxyl group in its molecular structure and the steric hindrance effect of the unsaturated polyether macromonomer side chain synergistically achieve adsorption and dispersion of cement particles; at the same time, it can also be nano-sized in aqueous solution. The nano-aggregates exist in the form of aggregates, and the nano-aggregates themselves also have a steric hindrance effect, which further makes it exhibit more excellent water-reducing and dispersing properties. The important thing is the hydrophobic functional monomer B. The present invention uses two types of hydrophobic functional monomers, tert-butyl acrylate and tert-butyl vinyl carbonate. When the two are used simultaneously and mixed in equal proportions, the hydrophilic-lipophilic balance (HLB) of the system can be synergistically regulated to achieve the viscosity reduction function. At the same time, the combination of tert-butyl acrylate and tert-butyl vinyl carbonate can effectively and slowly hydrolyze the ester group in the alkaline environment of cement concrete to release the functional carboxylic acid group, so that the functional polyacrylate macromolecule also exhibits excellent sustained-release and collapse-retention properties.

[0023] (2) The present invention uses unsaturated polyether macromonomers commonly used in the preparation of commercially available polycarboxylic acid water-reducing agents as the main raw material, which has obvious cost advantages. In addition, by optimizing and regulating the types and ratios of acrylic acid (ester) monomers and functional monomers A and B, a functional polyacrylate macromolecule is obtained. When used as a concrete water-reducing agent, it not only has good water-reducing and dispersing properties, but also has significant viscosity reduction and slow-release slump-retention effects. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0025] Example 1

[0026] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0027] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of sodium vinyl sulfonate, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of vinyl ester carbonate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isobutylene polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0028] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0029] Example 2

[0030] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0031] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of sodium vinyl sulfonate, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of vinyl ester carbonate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0032] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0033] Example 3

[0034] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0035] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.0 kg of sodium vinyl sulfonate, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.35 kg of tert-butyl acrylate, 0.35 kg of vinyl ester carbonate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0036] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0037] Example 4

[0038] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0039] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of tert-butyl acrylate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isobutylene polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0040] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0041] Example 5

[0042] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0043] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of tert-butyl acrylate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0044] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0045] Example 6

[0046] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0047] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.4 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.4 kg of tert-butyl acrylate, 0.4 kg of tert-butyl carbonate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0048] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0049] Example 7

[0050] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0051] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.4 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.3 kg of tert-butyl acrylate, 0.3 kg of tert-butyl acrylate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0052] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0053] Example 8

[0054] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0055] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.4 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.35 kg of tert-butyl acrylate, 0.35 kg of tert-butyl acrylate, and 3.2 kg of acrylic acid were added in sequence and stirred vigorously for 0.5 h. Then, 35.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0056] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0057] Example 9

[0058] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0059] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of sodium vinyl sulfonate, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of vinyl ester carbonate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isobutylene polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0060] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0061] Example 10

[0062] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0063] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of sodium vinyl sulfonate, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of vinyl ester carbonate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0064] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0065] Example 11

[0066] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0067] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.9 kg of sodium vinyl sulfonate, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.35 kg of tert-butyl acrylate, 0.35 kg of vinyl ester carbonate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0068] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0069] Example 12

[0070] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0071] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of tert-butyl acrylate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isobutylene polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0072] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0073] Example 13

[0074] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0075] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 1.7 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of tert-butyl acrylate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0076] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0077] Example 14

[0078] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0079] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.2 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.35 kg of tert-butyl acrylate, 0.35 kg of tert-butyl acrylate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0080] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0081] Example 15

[0082] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0083] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.4 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.35 kg of tert-butyl acrylate, 0.35 kg of tert-butyl acrylate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isobutylene polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0084] (2) Preparation of polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0085] Example 16

[0086] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0087] (1) Preparation of mixed monomer pre-emulsion: 50.0 kg of deionized water, 5 kg of sodium vinyl sulfonate, and 0.2 kg of potassium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.4 kg of tert-butyl acrylate, 0.4 kg of vinyl ester carbonate, and 10 kg of acrylic acid were added in sequence and stirred vigorously for 60 min. Then, 50.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0088] (2) Preparation of polyacrylate macromolecules: Add 10 kg of deionized water to the polymerization kettle, stir and heat to 90 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 180 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0089] Example 17

[0090] A method for preparing a viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following steps:

[0091] (1) Preparation of mixed monomer pre-emulsion: 20.0 kg of deionized water, 1 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of sodium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.25 kg of tert-butyl acrylate, 0.25 kg of tert-butyl acrylate, and 1 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 60 min. Then, 20.0 kg of isobutylene polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0092] (2) Preparation of polyacrylate macromolecules: Add 30 kg of deionized water to the polymerization kettle, stir and heat to 70 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 120 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

[0093] Comparative Example 1

[0094] A method for preparing polyacrylate macromolecules comprises the following steps:

[0095] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.2 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.7 kg of tert-butyl acrylate and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0096] (2) Preparation of functional polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain polyacrylate macromolecules.

[0097] In this comparative example, relative to Example 14, except that only tert-butyl acrylate was used in functional monomer B, the rest of the raw materials and preparation methods were the same as those in Example 14.

[0098] Comparative Example 2

[0099] A method for preparing polyacrylate macromolecules comprises the following steps:

[0100] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.2 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.7 kg of tert-butyl acrylate and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0101] (2) Preparation of functional polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain polyacrylate macromolecules.

[0102] This comparative example is the same as Example 14 except that only tert-butyl ester is used in the functional monomer B. The rest of the raw materials and preparation method are the same as Example 14.

[0103] Comparative Example 3

[0104] A method for preparing polyacrylate macromolecules comprises the following steps:

[0105] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.2 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 4.5 kg of β-carboxyethyl acrylate was added and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0106] (2) Preparation of functional polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain polyacrylate macromolecules.

[0107] This comparative example is the same as Example 14 except that functional monomer B is not used. Other raw materials and preparation methods are the same as Example 14.

[0108] Comparative Example 4

[0109] A method for preparing polyacrylate macromolecules comprises the following steps:

[0110] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.2 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.5 kg of tert-butyl acrylate, 0.2 kg of tert-butyl carbonate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0111] (2) Preparation of functional polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain polyacrylate macromolecules.

[0112] In this comparative example, as compared with Example 14, except for changing the ratio of tert-butyl acrylate and tert-butyl carbonate in functional monomer B, the rest of the raw materials and preparation method are the same as those in Example 14.

[0113] Comparative Example 5

[0114] A method for preparing polyacrylate macromolecules comprises the following steps:

[0115] (1) Preparation of mixed monomer pre-emulsion: 45.0 kg of deionized water, 2.2 kg of 2-acrylamido-2-methylpropanesulfonic acid, and 0.2 kg of ammonium persulfate were added to a mixing kettle and stirred to dissolve. Then, 0.2 kg of tert-butyl acrylate, 0.5 kg of tert-butyl carbonate, and 4.5 kg of β-carboxyethyl acrylate were added in sequence and stirred vigorously for 0.5 h. Then, 32.0 kg of isopentenyl polyethylene glycol ether (Mw≈2400) was added and stirred for 20 min to obtain a mixed monomer pre-emulsion.

[0116] (2) Preparation of functional polyacrylate macromolecules: Add 15.0 kg of deionized water to the polymerization kettle, stir and heat to 80 °C, start to drop the mixed monomer pre-emulsion, control the dropwise addition time to 150 min, continue to keep warm and react for 120 min after the dropwise addition is completed, then cool to 30-40 °C, adjust the pH value to 7-8 with ammonia water, and obtain polyacrylate macromolecules.

[0117] In this comparative example, as compared with Example 14, except for changing the ratio of tert-butyl acrylate and tert-butyl carbonate in functional monomer B, the rest of the raw materials and preparation method are the same as those in Example 14.

[0118] Performance Testing

[0119] The functional polyacrylate macromolecules designed and prepared in this invention are primarily used as water reducers. Therefore, their particle size and distribution, water dispersibility, and viscosity reduction performance were tested and characterized using the same performance testing methods for polycarboxylate water reducers. First, using a commercially available polycarboxylate water reducer (PCE1) and a commercially available viscosity-reducing polycarboxylate water reducer (PCE2) as controls, the aggregation morphology of the functional polyacrylate macromolecules in aqueous solution was measured and characterized using a Brookhaven Zeta potential and particle size analyzer. The results are shown in Table 1.

[0120] Table 1 Particle size and distribution of polyacrylate macromolecules prepared in typical examples

[0121]

[0122]

[0123] As can be seen from the table, the functional polyacrylate macromolecules designed and prepared by the present invention mainly exist in the form of aggregates in aqueous solution. This is because the functional monomers B involved in the present invention are all hydrophobic functional components, and the present invention is cleverly designed to make use of the dual functions of emulsification and reactivity of functional monomer A to effectively achieve emulsification, solubilization and emulsion polymerization, thereby obtaining a functional polyacrylate macromolecule solution with a certain particle size and distribution.

[0124] Table 2 Fluidity and viscosity of cement paste of polyacrylate macromolecules prepared in typical examples

[0125]

[0126]

[0127] Secondly, referring to the national standard GB / T 8076-2008 "Concrete Admixtures", the initial and time-dependent fluidity of the cement paste containing the polyacrylate macromolecules of the present invention was measured. Finally, in order to characterize the viscosity-reducing performance of the polyacrylate macromolecules, the present invention adopted two methods to measure and evaluate their viscosity-reducing performance. Method 1 refers to the cement paste flow test method in GB / T8076-2008 "Concrete Admixtures", controlling the water-cement ratio to 0.29, and adjusting the amount of polyacrylate macromolecules (0.2% ± 0.05 of the weight of the cementitious material) to make the fluidity of the cement paste reach (250 ± 5) mm. The apparent viscosity of the cement paste is then measured using an NDJ-8 rotational viscometer (rotor No. 2, speed 3 rpm). Method 2 refers to JC / T1083-2008, "Test Method for Compatibility of Cement and Water-Reducing Agents," and measures Marsh time: The water-cement ratio is controlled at 0.24, and the dosage of the functionalized polyacrylate macromolecule is adjusted to achieve a slurry fluidity of (220 ± 5) mm. The draining time is then accurately recorded. The results of the cement slurry fluidity and viscosity of the polyacrylate macromolecule prepared in a typical embodiment of the present invention are shown in Table 2.

[0128] The results show that compared with the commercially available polycarboxylate water-reducing agent (PCE1), the polyacrylate macromolecules of the present invention also exhibit excellent water-reducing and dispersing properties. This is because the polyacrylate macromolecules of the present invention not only use the unsaturated polyether macromonomer commonly used in the preparation of commercially available polycarboxylate water-reducing agents as the main raw material, but also exist in the form of nano-aggregates in aqueous solution with a particle size of about 30-150nm. The surface hydrophilic carboxylic acid functional groups of the nano-aggregates are adsorbed on the surface of cement particles. At the same time, the steric hindrance effect of the unsaturated polyether macromonomer side chains effectively blocks the aggregation and further hydration of cement particles, thereby exhibiting excellent water-reducing and dispersing properties. In addition, the polyacrylate macromolecules exist in the form of nano-aggregates in aqueous solution, and the nano-aggregates themselves also have a steric hindrance effect, which further enables them to exhibit excellent water-reducing and dispersing properties. Moreover, the hydrophobic functional monomer B can slowly undergo ester hydrolysis reaction in the alkaline environment of cement concrete to release functional carboxylic acid groups, so the functional polyacrylate macromolecules also exhibit excellent slow-release and slump-retaining properties. In terms of viscosity reduction performance, compared with a commercially available viscosity-reducing polycarboxylate water-reducing agent (PCE2) and Comparative Examples 1-5, the cement paste viscosity of the examples was significantly reduced, and the emptying time of the inverted slump cone was significantly shortened, demonstrating excellent viscosity reduction. The effective introduction of hydrophobic functional monomer B significantly improves the hydrophilic-lipophilic balance (HLB) of the functional polyacrylate macromolecule, thereby imparting significant viscosity reduction performance. However, in Comparative Examples 1-5, which alter the monomer composition and dosage ratio of functional monomer B, the synergistic effect between the two hydrophobic functional monomers, tert-butyl acrylate and tert-butyl vinyl carbonate, is disrupted, weakening their functionality, reducing their ability to adjust the HLB, and accelerating the ester bond hydrolysis rate, leading to a decline in overall performance.

[0129] It can be seen that the selection of functional monomer B in the present invention is the key to achieving the sustained-release and viscosity-reducing effect. The two types of hydrophobic functional monomers, tert-butyl acrylate and tert-butyl carbonate, cooperate synergistically to form an organic whole. If one of them is missing, the effect will be weakened.

[0130] In summary, the novel polyacrylate macromolecules involved in the present invention use unsaturated polyether macromonomers commonly used in the preparation of commercially available polycarboxylate water-reducing agents as the main raw material. By optimizing and regulating the types and ratios of acrylic acid (ester) monomers and functional monomers A and B, a functional polyacrylate macromolecule is obtained. When used as a concrete water-reducing agent, it not only exhibits excellent water-reducing and dispersing properties, but also has significant viscosity-reducing efficiency. Furthermore, this functional polyacrylate macromolecule is mainly based on unsaturated polyether macromonomers commonly used in the preparation of commercially available polycarboxylate water-reducing agents as the main raw material, which has significant cost advantages and is very conducive to industrial application and promotion, thus having broad application prospects.

[0131] It should be noted that the above embodiments are only some of the preferred embodiments of the present invention, and not all of them. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

Claims

1. A viscosity reducing and sustained-release polyacrylate macromolecule, characterized in that Prepared by emulsion polymerization of acrylic monomers, unsaturated polyether macromonomers, functional monomers A and functional monomers B; the acrylic monomers are acrylic acid and / or β-carboxyethyl acrylate; the unsaturated polyether macromonomers are isobutylene polyethylene glycol ether HPEG and / or isopentenyl polyethylene glycol ether TPEG; the functional monomer A is one of sodium vinyl sulfonate and 2-acrylamido-2-methylpropanesulfonic acid; the functional monomer B is a combination of tert-butyl acrylate and tert-butyl carbonate; the mass ratio of tert-butyl acrylate to tert-butyl carbonate in the functional monomer B is 1:1; the preparation method of the viscosity-reducing and sustained-release polyacrylate macromolecule comprises the following preparation steps, calculated by mass: (1) Preparation of mixed monomer pre-emulsion: Add 20.0-50.0 parts of deionized water, 1.0-5.0 parts of functional monomer A and 0.2 parts of initiator to a mixing kettle and stir to dissolve them. Then, add 0.5-0.8 parts of functional monomer B and 1.0-10.0 parts of acrylic monomer in sequence and stir vigorously for 30-60 minutes. Then, add 20.0-50.0 parts of unsaturated polyether macromonomer and stir for 20 minutes to obtain a mixed monomer pre-emulsion. (2) Preparation of polyacrylate macromolecules: Add 10.0-30.0 parts of deionized water to the polymerization kettle, stir and heat to 70-90°C, then start to drop the mixed monomer pre-emulsion and control the dropwise addition time to 120-180min. After the dropwise addition is completed, continue to keep the temperature and react for 120min, then cool to 30-40°C, and adjust the pH value to 7-8 with ammonia water to obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

2. A method for preparing the viscosity-reducing and sustained-release polyacrylate macromolecule according to claim 1, comprising the following preparation steps, calculated by weight: (1) Preparation of mixed monomer pre-emulsion: Add 20.0-50.0 parts of deionized water, 1.0-5.0 parts of functional monomer A and 0.2 parts of initiator to a mixing kettle and stir to dissolve them. Then, add 0.5-0.8 parts of functional monomer B and 1.0-10.0 parts of acrylic monomer in sequence and stir vigorously for 30-60 minutes. Then, add 20.0-50.0 parts of unsaturated polyether macromonomer and stir for 20 minutes to obtain a mixed monomer pre-emulsion. (2) Preparation of polyacrylate macromolecules: Add 10.0-30.0 parts of deionized water to the polymerization kettle, stir and heat to 70-90°C, then start to drop the mixed monomer pre-emulsion and control the dropwise addition time to 120-180min. After the dropwise addition is completed, continue to keep the temperature and react for 120min, then cool to 30-40°C, and adjust the pH value to 7-8 with ammonia water to obtain the viscosity-reducing and sustained-release polyacrylate macromolecules.

3. The method for preparing the viscosity-reducing and sustained-release polyacrylate macromolecule according to claim 2, characterized in that: The initiator in step (1) is one or more of ammonium persulfate, potassium persulfate, and sodium persulfate.

4. An application of the viscosity-reducing and sustained-release polyacrylate macromolecule according to claim 1, characterized in that: It is used as a water reducing agent in the fields of concrete, waterproofing and gypsum boards.

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