CN116239732B - Modified polycarboxylic acid high-performance water reducer and preparation method thereof - Google Patents
Modified polycarboxylic acid high-performance water reducer and preparation method thereof Download PDFInfo
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- CN116239732B CN116239732B CN202310199323.7A CN202310199323A CN116239732B CN 116239732 B CN116239732 B CN 116239732B CN 202310199323 A CN202310199323 A CN 202310199323A CN 116239732 B CN116239732 B CN 116239732B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
- C08F283/06—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2688—Copolymers containing at least three different monomers
- C04B24/2694—Copolymers containing at least three different monomers containing polyether side chains
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
- C08G65/32—Polymers modified by chemical after-treatment
- C08G65/329—Polymers modified by chemical after-treatment with organic compounds
- C08G65/336—Polymers modified by chemical after-treatment with organic compounds containing silicon
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/302—Water reducers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention belongs to the technical field of high polymer materials, and discloses a modified polycarboxylic acid high-performance water reducer and a preparation method thereof. The preparation method comprises the following steps: adding a polyether macromonomer and a hydrogen-containing silane coupling agent into an organic solvent, uniformly mixing, heating to 60-100 ℃, adding a catalyst for dehydrogenation condensation reaction, and removing the solvent and low-boiling substances under reduced pressure after the reaction is finished to obtain a silane modified polyether macromonomer; adding the obtained silane modified polyether macromonomer and acrylic acid into water, stirring and heating to 60-80 ℃, dripping an initiator for reaction, then adding an ETPTA cross-linking agent and a chain transfer agent, and continuing stirring and reacting to obtain the modified polycarboxylic acid high-performance water reducer. The modified polycarboxylic acid high-performance water reducer can achieve excellent slump retaining effect and dispersion property simultaneously through the synergistic opposite impact effect of the hydrolyzable silane modified polyether macromonomer and ETPTA partial crosslinking.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and particularly relates to a modified polycarboxylic acid high-performance water reducer and a preparation method thereof.
Background
The water reducing agent is a concrete admixture capable of reducing the mixing water consumption under the condition of maintaining the slump constant of the concrete. The water reducer can ensure the high strength and good durability of the concrete, and is one of the indispensable components of the modern concrete. The high-efficiency water reducer which is commonly used at present mainly comprises naphthalene-based, sulfonated melamine resin-based, fatty acid-based, sulfamate-based, modified lignin sulfonate-based and polycarboxylic acid-based water reducers. The polycarboxylic acid high-performance water reducer has rapid development and application, and can be widely applied to projects such as water conservancy, hydropower, hydraulic engineering, maritime engineering, bridges and the like.
At present, the polycarboxylic acid water reducer mainly comprises the following 3 types: 1. an ester polycarboxylic acid water reducer, namely a water reducer prepared by taking methoxy polyethylene glycol mono (methyl) acrylate as a polyoxyethylene-based macromonomer; 2. the common ether polycarboxylate water reducer is a water reducer prepared by taking allyl polyethylene glycol or a modified product thereof as a main polyoxyethylene-based macromonomer; 3. the modified ether polycarboxylate water reducer is a water reducer prepared by taking methyl allyl polyethylene glycol or a modified product thereof as a main polyoxyethylene-based macromonomer. After the polyester is introduced into the polycarboxylate water reducer, partial acrylic acid is replaced on the main chain of the water reducer, and the polyester has the characteristic of ester macromonomer, and is hydrolyzed in the alkaline environment of the cement paste, so that carboxyl is continuously released for a long time, the adsorption and dispersion capacity of the water reducer in the later stage of molecules is improved, and the slump retaining performance of the water reducer is improved. Compared with polyester water reducer, the common polyether water reducer has low cost, simple synthesis process and high polymerization concentration, but has lower water reducing rate, slump retaining performance and cement adaptability than the polyester water reducer, and has narrower application range when being singly used. The modified ether polycarboxylate water reducer has the advantages of high water reducing rate, good slump retaining performance, good cement adaptability and the like of the polyester water reducer, and has the advantages of simple synthesis process, high polymerization concentration and the like of the common polyether water reducer, so that the modified ether polycarboxylate water reducer becomes a hot spot for researching the existing polycarboxylate water reducer.
In general, the main chain of polycarboxylic acid in the polycarboxylic acid water reducer mainly plays an adsorption role, is directionally adsorbed on the surfaces of cement particles, so that the surfaces of the cement particles have the same charge to form an electrostatic repulsive force, the cement particles are mutually dispersed, a flocculation structure is disintegrated, and part of water coated on the main chain is released to participate in flowing, so that the fluidity of the concrete mixture is effectively increased. Meanwhile, the water-reducing adsorption film on the surface of the cement particles can form a layer of stable solvated water film with water molecules by utilizing the strong polar hydrophilic group in the water reducer, and the water film has good lubricating effect and can effectively reduce the sliding resistance among the cement particles, so that the fluidity of the concrete is further improved, and the water-reducing rate is improved. However, the simple polycarboxylate water reducer has smaller steric hindrance and poorer dispersion retention, so the slump retention is poorer. The hydrophilic branched chain is introduced into the water reducing agent structure and stretched into the water solution, so that a hydrophilic three-dimensional adsorption layer with a certain thickness is formed on the surface of the adsorbed cement particles. When the cement particles are close, the larger the steric hindrance is generated among the cement particles, the larger the inhibition to the agglomeration among the cement particles is, so that the slump of the concrete is kept good. However, too large steric hindrance also reduces its directional adsorption performance, and when the branched chain density increases, the adsorption groups become smaller, and the side chain spacing becomes smaller, so that entanglement is easy to occur, which is unfavorable for maintaining the dispersion performance. Therefore, how to adjust the directional adsorption performance and the steric hindrance of the polycarboxylic acid water reducer to achieve good dispersibility and dispersion stability is a technical problem to be solved by the person skilled in the art.
Patent CN 111732697A discloses a silane modified polycarboxylate water reducer, wherein a specific silane, specific polyoxyethylene ether and acrylic acid are selected to react, and a silane coupling agent is copolymerized on a main chain to realize a certain anchoring effect. But the adopted silane coupling agent has shorter molecular chain and limited anchoring effect under the steric hindrance of long-chain polyoxyethylene ether. Patent CN 107163201A discloses a method for preparing slump retaining type polycarboxylate superplasticizer by modifying polyether with a silane coupling agent. The polycarboxylate water reducer is prepared by using a silane coupling agent, a polyether compound, an unsaturated carboxylic acid monomer and the like as main reaction raw materials through a method of firstly hydrolyzing, then carrying out Williamson etherification, then condensing and then copolymerizing. The polycarboxylic acid water reducer with a plurality of branched silane coupling agents for modifying polyether side chains successfully realizes a strong steric hindrance effect and has more excellent slump retaining characteristics than the common polycarboxylic acid water reducer. But the silane coupling agent capable of generating an anchoring effect is positioned at the polymerization end, and the anchoring effect is limited under the steric hindrance of the terminal long-chain polyoxyethylene ether, and meanwhile, the directional adsorption performance of the silane coupling agent is reduced due to the strong steric hindrance effect, so that the dispersibility is reduced. Patent CN112979887a discloses a modified polycarboxylate water reducer, which adopts long-chain fluorosilane and a multi-branch structure obtained by reacting with a vinyl silane coupling agent as a modified monomer, has large steric hindrance, does not affect the hydrophilic lubrication effect of the water reducer under a proper dosage, is favorable for blocking the agglomeration effect among cement particles after the water reducer molecules are directionally adsorbed on the surfaces of the cement particles, has an excellent slump retaining effect, and still has a reduction of dispersion performance.
Disclosure of Invention
Aiming at the defects and shortcomings of the prior art, the primary aim of the invention is to provide a preparation method of a modified polycarboxylic acid high-performance water reducer.
The invention also aims to provide the modified polycarboxylic acid high-performance water reducer prepared by the method.
The invention aims at realizing the following technical scheme:
the preparation method of the modified polycarboxylic acid high-performance water reducer comprises the following preparation steps:
(1) Adding a polyether macromonomer and a hydrogen-containing silane coupling agent into an organic solvent, uniformly mixing, heating to 60-100 ℃, adding a catalyst for dehydrogenation condensation reaction, and removing the solvent and low-boiling substances under reduced pressure after the reaction is finished to obtain a silane modified polyether macromonomer;
(2) Adding the silane modified polyether macromonomer obtained in the step (1) and acrylic acid into water, stirring and heating to 60-80 ℃, dropwise adding an initiator for reaction, then adding an ethoxylation trimethylolpropane triacrylate (ETPTA) cross-linking agent and a chain transfer agent, and continuing stirring and reacting to obtain the modified polycarboxylic acid high-performance water reducer.
Further, in the step (1), the polyether macromonomer is (methyl) allyl polyoxyethylene ether, isobutenyl alcohol polyoxyethylene ether or isopentenyl alcohol polyoxyethylene ether.
Further, the hydrogen-containing silane coupling agent in the step (1) is trimethoxy silane, triethoxy silane, methyl dimethoxy silane or methyl diethoxy silane.
Further, the molar ratio of the polyether macromonomer to the hydrogen-containing silane coupling agent in the step (1) is 1:1.2-2.
Further, the organic solvent in the step (1) is one or more than two solvents selected from ethanol, propanol, isopropanol, tetrahydrofuran and N, N-dimethylformamide.
Further, the catalyst in the step (1) is an acetylacetone metal complex or an organotin compound; preferably, the metal acetylacetonate complex is zinc acetylacetonate or iron acetylacetonate, and the organotin compound is dibutyltin dilaurate or dibutyltin diacetate.
Further, the mass ratio of the silane modified polyether macromonomer to the acrylic acid added in the step (2) is 5-25:1.
Further, the initiator in the step (2) is ammonium persulfate, potassium persulfate or sodium persulfate.
Further, the addition amount of the ETPTA cross-linking agent in the step (2) is 0.1-5% of the mass of the silane modified polyether macromonomer.
Further, the chain transfer agent in step (2) is mercaptopropionic acid, mercaptoethanol or mercaptopropanol.
The modified polycarboxylic acid high-performance water reducer is prepared by the method.
The principle of the invention is as follows: the silane modified polyether macromonomer of the terminal silane coupling agent is formed by dehydrogenating and condensing the polyether macromonomer and the hydrogen-containing silane coupling agent, and then is copolymerized with acrylic acid and is crosslinked through ETPTA to obtain the silane modified polyether macromonomer branched chain with certain density and the modified polycarboxylate water reducer with partial crosslinking. Wherein, both the silane modified polyether branched chain and the partial crosslinking can increase the steric hindrance effect of the system, and the slump retaining characteristic is excellent. Meanwhile, the anchoring effect of the silane modified polyether macromonomer of the terminal silane coupling agent and cement particles is not influenced by steric hindrance of the polyether macromonomer, the anchoring effect is stronger than the directional adsorption effect of acrylic acid, and the reduction of the directional adsorption effect of an acrylic acid main chain caused by the steric hindrance effect can be effectively compensated, so that the excellent dispersibility is shown. Meanwhile, when the modified cement paste is applied in an alkaline environment of cement paste, both the silane modified polyether macromonomer and the ETPTA crosslinking part of the terminal silane coupling agent can be hydrolyzed, the hydrolysis of the silane modified polyether macromonomer reduces the directional adsorption effect, and the hydrophilic polyether branched chain extends into the aqueous solution, so that a hydrophilic three-dimensional adsorption layer with a certain thickness is formed on the surface of the adsorbed cement particles. When the cement particles are close to each other, the larger the steric hindrance is generated among the cement particles, the larger the inhibition of the agglomeration among the cement particles is, and meanwhile, the silane compound remained on the surfaces of the cement particles forms an inner hydrophobic layer to further inhibit the agglomeration among the cement particles, so that the slump of the concrete is kept good. And ETPTA crosslinked part is hydrolyzed to release more water reducer molecules, so that carboxyl is continuously released in a longer time, the directional adsorption effect is enhanced, and the later adsorption and dispersion capacity of the water reducer molecules is improved, so that the dispersion stability of the water reducer is maintained. In short, the modified polycarboxylic acid high-performance water reducer increases the steric hindrance effect of the system through polyether macromonomer branched chains and partial crosslinking in the early stage, and reduces the directional adsorption effect caused by the steric hindrance effect through the anchoring effect opposite impact of the terminal silane coupling agent; in the later stage, the hydrolysis of the silane modified polyether macromonomer is used for blocking the agglomeration among cement particles, and meanwhile, the directional adsorption effect caused by the hydrolysis of the ETPTA crosslinking partial hydrolysis hedging silane modified polyether macromonomer is reduced, and the excellent slump retaining effect and dispersion property are achieved through the synergistic hedging effect of the ETPTA crosslinking partial hydrolysis hedging silane modified polyether macromonomer.
Compared with the prior art, the invention has the beneficial effects that:
the modified polycarboxylic acid high-performance water reducer can achieve excellent slump retaining effect and dispersion property simultaneously through the synergistic opposite impact effect of the hydrolyzable silane modified polyether macromonomer and ETPTA partial crosslinking.
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the present invention are not limited thereto.
Example 1
The preparation method of the modified polycarboxylic acid high-performance water reducer comprises the following preparation steps:
(1) 100g of polyether macromonomer methylallyl polyoxyethylene ether (HPEG-2400) and 10g of triethoxy hydrosilane as a hydrogen-containing silane coupling agent are added into 300ml of isopropanol solvent to be uniformly mixed, and then the temperature is raised to 75 ℃ to the upper partAdding catalyst zinc acetylacetonate for thermal insulation reaction for 4h at 80 ℃, and removing solvent and low-boiling-point substances by reduced pressure distillation after the reaction is completed to obtain silane modified polyether macromonomer HPEG-Si (OEt) 3 。
(2) Adding 100g of the silane modified polyether macromonomer obtained in the step (1) and 20g of acrylic acid into 150ml of water, stirring and heating to 75-80 ℃, dropwise adding an initiator ammonium persulfate for heat preservation reaction for 2h, dropwise adding the initiator for 2h, then adding 1.2g of ETPTA cross-linking agent and 0.2g of chain transfer agent mercaptoethanol, and continuously stirring and reacting for 4h to obtain the modified polycarboxylic acid high-performance water reducer.
Example 2
The preparation method of the modified polycarboxylic acid high-performance water reducer comprises the following preparation steps:
(1) 100g of polyether macromonomer isopentenol polyoxyethylene ether (TPEG-2400) and 8g of hydrogen-containing silane coupling agent methyl diethoxy hydrosilane are added into 300ml of isopropanol solvent to be uniformly mixed, then the temperature is raised to 85-90 ℃, the catalyst ferric acetylacetonate is added for thermal insulation reaction for 6 hours, and after the reaction is completed, the solvent and low-boiling substances are removed by reduced pressure distillation, thus obtaining silane modified polyether macromonomer TPEG-SiMe (OEt) 2 。
(2) 100g of the silane modified polyether macromonomer obtained in the step (1) and 20g of acrylic acid are added into 150ml of water, the temperature is raised to 75-80 ℃ by stirring, an initiator ammonium persulfate is dropwise added for carrying out heat preservation reaction for 2h, the initiator is dropwise added for 2h, then 1.5g of ETPTA cross-linking agent and 0.2g of chain transfer agent mercaptopropanol are added for continuous stirring reaction for 4h, and the modified polycarboxylic acid high-performance water reducer is obtained.
Example 3
The preparation method of the modified polycarboxylic acid high-performance water reducer comprises the following preparation steps:
(1) Adding 100g of polyether macromonomer allyl polyoxyethylene ether (APEG-1200) and 15g of trimethoxy silane serving as a hydrogen-containing silane coupling agent into 300ml of N, N-dimethylformamide solvent, uniformly mixing, heating to 75-80 ℃, adding catalyst dibutyl tin dilaurate for heat preservation reaction for 5h, and removing the solvent and low-boiling substances by reduced pressure distillation after the reaction is finished to obtain silane modified polyether macromonomer APEG-Si (OMe) 3 。
(2) Adding 100g of the silane modified polyether macromonomer obtained in the step (1) and 20g of acrylic acid into 150ml of water, stirring and heating to 75-80 ℃, dropwise adding initiator potassium persulfate for heat preservation reaction for 1.5h, dropwise adding the initiator for 1.5h, then adding 1.0g of ETPTA cross-linking agent and 0.3g of chain transfer agent mercaptopropanol, and continuing stirring and reacting for 3h to obtain the modified polycarboxylic acid high-performance water reducer.
Comparative example 1
In comparison with example 1, the polyether macromonomer methallyl polyoxyethylene ether was not modified with a silane coupling agent, comprising the following preparation steps:
100g of polyether macromonomer methyl allyl polyoxyethylene ether (HPEG-2400) and 20g of acrylic acid are added into 150ml of water, the temperature is raised to 75-80 ℃ by stirring, the initiator ammonium persulfate is added dropwise for carrying out heat preservation reaction for 2h, the initiator is added dropwise for 2h, then 1.5g of ETPTA cross-linking agent and 0.2g of chain transfer agent mercaptoethanol are added for continuous stirring reaction for 4h, and the modified polycarboxylate water reducer is obtained.
Comparative example 2
In this comparative example, as compared with example 1, the crosslinking reaction was performed without adding the ETPTA crosslinking agent, comprising the following preparation steps:
(1) Adding 100g of polyether macromonomer methyl allyl polyoxyethylene ether (HPEG-2400) and 10g of hydrogen-containing silane coupling agent triethoxy hydrosilane into 300ml of isopropanol solvent, uniformly mixing, heating to 75-80 ℃, adding catalyst zinc acetylacetonate for thermal insulation reaction for 4h, and removing solvent and low-boiling substances by reduced pressure distillation after the reaction is completed to obtain silane modified polyether macromonomer HPEG-Si (OEt) 3 。
(2) And (2) adding 100g of the silane modified polyether macromonomer obtained in the step (1) and 20g of acrylic acid into 150ml of water, stirring and heating to 75-80 ℃, dropwise adding an initiator ammonium persulfate for heat preservation reaction for 2h, dropwise adding the initiator for 2h, and then adding 0.2g of a chain transfer agent mercaptoethanol for continuous stirring reaction for 4h to obtain the modified polycarboxylate water reducer.
Comparative example 3
This comparative example, compared to example 1, uses polyethylene glycol dimethacrylate (PEGDMA) instead of ETPTA crosslinker, comprising the following preparation steps:
(1) Adding 100g of polyether macromonomer methyl allyl polyoxyethylene ether (HPEG-2400) and 10g of hydrogen-containing silane coupling agent triethoxy hydrosilane into 300ml of isopropanol solvent, uniformly mixing, heating to 75-80 ℃, adding catalyst zinc acetylacetonate for thermal insulation reaction for 4h, and removing solvent and low-boiling substances by reduced pressure distillation after the reaction is completed to obtain silane modified polyether macromonomer HPEG-Si (OEt) 3 。
(2) 100g of the silane modified polyether macromonomer obtained in the step (1) and 20g of acrylic acid are added into 150ml of water, the temperature is raised to 75-80 ℃ by stirring, an initiator ammonium persulfate is dropwise added for carrying out heat preservation reaction for 2h, the initiator is dropwise added for 2h, then 1.5g of PEGDMA cross-linking agent and 0.2g of chain transfer agent mercaptoethanol are added for continuous stirring reaction for 4h, and the modified polycarboxylate water reducer is obtained.
Application effect test of the modified polycarboxylate water reducer obtained in the above examples and comparative examples:
the modified polycarboxylate water reducers obtained in the above examples and comparative examples were tested for water reduction rate, cement paste fluidity and its time-lapse fluidity, slump retention (1 h slump loss) and 0.5h paste free bleeding rate, respectively. The cement used in the experiment is P.O42.5 standard cement, and the folding and solidifying mixing amount of the water reducing agent is 0.25%. The water reducing rate, the initial fluidity of the cement paste, the fluidity with time (1 h) and the slump are tested by referring to GB/8076-2008, and the free bleeding rate of the paste with time of 0.5h is measured by referring to JTG/TF 50-2011. The test results are shown in table 1 below.
TABLE 1
As can be seen from the results of Table 1, the polyether macromonomer of comparative example 1 was not modified with a silane coupling agent, and its water reduction rate and fluidity were significantly reduced, because the steric hindrance caused the decrease in the directional adsorption of the water reducing agent molecules to the surface of cement particles, and the dispersibility was reduced. The slump loss and bleeding rate of the cement mortar are obviously increased in 1h, and the reason is that the process of generating a hydrophobic layer in a silane compound by hydrolysis of a silane modified polyether macromonomer and forming a hydrophilic three-dimensional adsorption layer by stretching a polyether branched chain is lack, and the polyether branched chain is wound to a certain extent, so that the coagulation inhibition effect among cement particles is obviously reduced. Compared with the example 1, the comparative example 2 is free from adding ETPTA crosslinking agent for crosslinking reaction, the fluidity is obviously reduced, the slump loss and bleeding rate are obviously increased after 1h, and the reasons are that the directional adsorption effect caused by the hydrolysis of the later-stage silane modified polyether macromonomer is reduced, the dispersion retention is poor, and the agglomeration among cement particles is enhanced. Comparative example 3 the water reducing agent system of the present invention has limited performance improvement effect on the flow property, the 1h slump loss and the bleeding rate by using PEGDMA instead of ETPTA crosslinking agent as compared with example 1. From the above results, it is obvious that the invention can achieve very excellent slump retaining effect and dispersion property at the same time by the synergistic opposite impact of the partial crosslinking of the hydrolyzable silane modified polyether macromonomer and ETPTA.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (7)
1. The preparation method of the modified polycarboxylic acid high-performance water reducer is characterized by comprising the following preparation steps:
(1) Adding a polyether macromonomer and a hydrogen-containing silane coupling agent into an organic solvent, uniformly mixing, heating to 60-100 ℃, adding a catalyst for dehydrogenation condensation reaction, and removing the solvent and low-boiling substances under reduced pressure after the reaction is completed to obtain a silane modified polyether macromonomer;
(2) Adding the silane modified polyether macromonomer obtained in the step (1) and acrylic acid into water, stirring and heating to 60-80 ℃, dropwise adding an initiator for reaction, and then adding an ETPTA cross-linking agent and a chain transfer agent for continuous stirring reaction to obtain a modified polycarboxylic acid high-performance water reducer;
the polyether macromonomer in the step (1) is (methyl) allyl polyoxyethylene ether, isobutenyl alcohol polyoxyethylene ether or isopentenyl alcohol polyoxyethylene ether;
the mass ratio of the silane modified polyether macromonomer to the acrylic acid added in the step (2) is 5-25:1;
the addition amount of the ETPTA crosslinking agent in the step (2) is 0.1-5% of the mass of the silane modified polyether macromonomer.
2. The method for preparing a modified polycarboxylic acid high-performance water reducer according to claim 1, wherein the hydrogen-containing silane coupling agent in the step (1) is trimethoxy silane, triethoxy silane, methyl dimethoxy silane or methyl diethoxy silane.
3. The preparation method of the modified polycarboxylic acid high-performance water reducer according to claim 1, wherein the molar ratio of the polyether macromonomer to the hydrogen-containing silane coupling agent in the step (1) is 1:1.2-2.
4. The method for preparing a modified polycarboxylic acid high-performance water reducer according to claim 1, wherein the organic solvent in the step (1) is one or more solvents selected from ethanol, propanol, isopropanol, tetrahydrofuran and N, N-dimethylformamide.
5. The method for preparing a modified polycarboxylic acid high-performance water reducer according to claim 1, wherein the catalyst in the step (1) is an acetylacetone metal complex or an organotin compound; the metal acetylacetonate complex is zinc acetylacetonate or iron acetylacetonate, and the organotin compound is dibutyltin dilaurate or dibutyltin diacetate.
6. The method for preparing the modified polycarboxylic acid high-performance water reducer according to claim 1, wherein the initiator in the step (2) is ammonium persulfate, potassium persulfate or sodium persulfate; the chain transfer agent is mercaptopropionic acid, mercaptoethanol or mercaptopropanol.
7. The modified polycarboxylic acid high-performance water reducer is characterized by being prepared by the method of any one of claims 1-6.
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