CN114479057B - Ester monomer, polycarboxylate water reducer and preparation method thereof - Google Patents

Ester monomer, polycarboxylate water reducer and preparation method thereof Download PDF

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CN114479057B
CN114479057B CN202111618940.3A CN202111618940A CN114479057B CN 114479057 B CN114479057 B CN 114479057B CN 202111618940 A CN202111618940 A CN 202111618940A CN 114479057 B CN114479057 B CN 114479057B
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monomer
parts
acid
ester
unsaturated acid
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CN114479057A (en
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李格丽
邵幼哲
吴传灯
林志群
方云辉
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Kezhijie New Material Group Co Ltd
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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
    • C08G65/331—Polymers modified by chemical after-treatment with organic compounds containing oxygen
    • C08G65/332—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing carboxyl groups, or halides, or esters thereof
    • C08G65/3322—Polymers modified by chemical after-treatment with organic compounds containing oxygen containing carboxyl groups, or halides, or esters thereof acyclic
    • 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
    • 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
    • C08F283/065—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals on to unsaturated polyethers, polyoxymethylenes or polyacetals
    • 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
    • C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
    • C08F290/02—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated end groups
    • C08F290/06—Polymers provided for in subclass C08G
    • C08F290/062—Polyethers
    • 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
    • C08G65/26—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 from cyclic ethers and other compounds
    • C08G65/2603—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 from cyclic ethers and other compounds the other compounds containing oxygen
    • C08G65/2606—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 from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups
    • C08G65/2609—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 from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups containing aliphatic hydroxyl groups
    • 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
    • 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 relates to the field of concrete additives, and provides an ester monomer, a polycarboxylate water reducer and a preparation method thereof. The ester monomer is formed by reacting reactants comprising polyalcohol, epoxy monomer and unsaturated acid, wherein the epoxy monomer is one of ethylene oxide, epichlorohydrin, propylene oxide or epoxyhexane, and the unsaturated acid is acrylic acid or methacrylic acid. The polycarboxylate water reducer is formed by free radical polymerization of an ester monomer, a polyether monomer, unsaturated acid and double bond-containing hydroxycarboxylic acid ester, wherein the ester monomer is as follows: polyether monomer: unsaturated acid: the mass ratio of the hydroxy carboxylic ester containing double bonds is 1-5:150-200:10-30:1-5. The polycarboxylate water reducer prepared by the invention has the advantages that the ester group is introduced in a copolyester monomer mode, so that the carboxyl content is not reduced due to esterification, the polymerization activity is good, the water reducing and slump retaining effects are excellent, the biotoxicity is low, and the environmental protection performance is good.

Description

Ester monomer, polycarboxylate water reducer and preparation method thereof
Technical Field
The invention relates to the field of concrete additives, in particular to an ester monomer, a polycarboxylate water reducer and a preparation method thereof.
Background
The ester polycarboxylate water reducer has the advantages of high water reducing rate, good universality with aggregate, higher workability, lower sensitivity and the like, and is applied to the domestic and foreign markets in recent years. Common ester synthesis methods include solid acid catalysis, transesterification, phase transfer catalysis, and microwave synthesis. In the production of ester polycarboxylic acid water reducer, the common transesterification method generally comprises two steps, namely, preparing a polymeric monomer with molecular activity by adopting an indirect or indirect esterification method, and then polymerizing the prepared polymeric monomer serving as a raw material by using a copolymerization method to synthesize polyester polycarboxylic acid water reducer with different types or performances.
At present, the ester polycarboxylate water reducer is generally prepared by esterifying acrylic acid or methacrylic acid and polyethylene glycol monomethyl ether to synthesize a macromer and copolymerizing the macromer and other small-molecule monomers containing active groups, wherein after esterification, the carboxyl content of the macromer disappears or decreases, so that the performance of the prepared polycarboxylate water reducer is affected. Other substances are adopted to replace acrylic acid for esterification, but the polymerization activity of the selected substitute is poor, so that the polymerization activity of the prepared macromer is influenced, the polymerization activity of the next step is influenced, and the performance of the prepared polycarboxylate water reducer is finally influenced.
The Chinese patent with publication number of CN109369860A published in 2.22.2019 discloses a slow-release controllable polycarboxylate water reducer mother liquor and a preparation method thereof, wherein a large monomer TPEG, a monoester small monomer, a diester small monomer and a functional monomer are adopted as polymerization monomers, and a polycarboxylate water reducer polymer is subjected to partial hydrolysis by regulating the pH value to be strong alkaline, so that the slow release controllability of the polycarboxylate water reducer mother liquor is realized. However, the adopted diester small monomer does not contain hydroxyl components, the content of ester groups is limited, and the activity density of the adopted monoester small monomer is insufficient, so that the slump retaining performance of the polycarboxylate water reducer mother solution is limited.
Disclosure of Invention
In order to solve the defect of limited slump retaining performance of the polycarboxylate water reducer in the prior art, the invention provides an ester monomer which is generated by reacting reactants comprising polyalcohol, epoxy monomer and unsaturated acid, wherein the epoxy monomer is one of ethylene oxide, epichlorohydrin, propylene oxide or epoxyhexane, the unsaturated acid is acrylic acid or methacrylic acid, and the polyalcohol comprises the following components: epoxy monomer: the mass ratio of unsaturated acid is 3-5: 6-10: 9 to 15.
In one embodiment, the polyol is 3 to 5 parts, the epoxy monomer is 6 to 10 parts, and the unsaturated acid is 9 to 15 parts.
In one embodiment, the polyol is one of ethylene glycol, glycerol, trimethylolpropane, glucose, and sorbitol.
In one embodiment, the molecular weight of the ester monomer is 1000 to 3000.
In one embodiment, the ester monomer is formed by polymerizing the polyol with the epoxy monomer and esterifying with the unsaturated acid.
The invention also provides a preparation method of the ester monomer in the claims, which comprises the following specific steps: weighing a catalyst and the unsaturated acid to prepare a solution A; weighing the polyol, the epoxy monomer and the polymerization inhibitor, stirring uniformly, and heating at T 1 The solution A is added dropwise at the beginning, and the adding time is t 1 After the dripping is finished, at T 2 Constant temperature t at temperature 2 Ending when the acid value is M, and cooling to room temperature.
In one embodiment, the room temperature is 25 ℃ to 28 ℃.
In a preferred embodiment, the room temperature is 25 ℃.
In one embodiment of the preparation process, T 1 At 80-120 ℃, T 2 At 80-120 deg.C t 1 1 to 2 hours, t 2 3 to 5 hours, M is 6mg KOH/g to 10mg KOH/g, T 1 And T 2 The temperature may be the same or different.
In one embodiment of the preparation method, 3-5 parts of the polyol, 6-10 parts of the epoxy monomer, 9-15 parts of the unsaturated acid, 1-3 parts of the catalyst and 1-2 parts of the polymerization inhibitor.
In an embodiment of the preparation method, the polymerization inhibitor is one of hydroquinone, p-hydroxyanisole and tetramethyl piperidine oxynitride.
In one embodiment of the preparation method, the catalyst is one or two of N, N-dimethylaniline, tetraethylammonium bromide, dimethyl diamide and boron trichloride diethyl ether-stannic chloride.
The invention also provides a polycarboxylate water reducer, which is prepared by free radical polymerization of the ester monomer, the polyether monomer, the unsaturated acid and the double bond-containing hydroxycarboxylic acid ester in the technical scheme, wherein the ester monomer is as follows: the polyether monomer: the unsaturated acid: the mass ratio of the hydroxy carboxylic ester containing double bonds is 1-5:150-200:10-30:1-5.
In one embodiment, the polyether monomer is 150-200 parts, the ester monomer is 1-5 parts, the unsaturated acid is 10-30 parts, and the hydroxy carboxylic ester is 1-5 parts.
In a preferred embodiment, the catalyst further comprises 1-5 parts of an oxidizing agent, 2-10 parts of a reducing agent, 0.5-2 parts of a chain transfer agent and 300-350 parts of deionized water.
In one embodiment, the reaction product pH is adjusted using a liquid base.
In a preferred embodiment, the liquid-alkali mass fraction is 30% -32%.
In one embodiment, the unsaturated acid is methacrylic acid or acrylic acid.
In one embodiment, the polyether monomer is one of methallyl polyoxyethylene ether (HPEG), isopentenyl alcohol polyoxyethylene ether (TPEG) or ethylene glycol monovinyl polyethylene glycol ether (EPEG).
In a preferred embodiment, the polyether monomer has a molecular weight of 1200 to 5000.
In one embodiment, the double bond containing hydroxycarboxylic acid esters have the structure
R 1 Is alkenyl with 2-4 carbon atoms, R 2 Is an alkyl group having 1 to 6 carbon atoms. The double bond-containing hydroxycarboxylic acid ester contains active alpha-h, compared with a polycarboxylic acid water reducer adopting common hydroxycarboxylic acid esterThe conversion rate is higher, and the performance is better.
In a preferred embodiment, the alkenyl group contains only one double bond.
In one embodiment, the room temperature is 25 ℃ to 28 ℃.
In a preferred embodiment, the room temperature is 25 ℃.
The invention also provides a preparation method of the polycarboxylate superplasticizer, which is characterized by comprising the following specific steps: dissolving a reducing agent in deionized water to obtain a solution B; dissolving unsaturated acid and the hydroxy carboxylic ester containing double bonds in deionized water to obtain a solution C; dissolving a chain transfer agent in deionized water to obtain a solution D; mixing the polyether monomer, the ester monomer and the initiator with deionized water, uniformly stirring at room temperature, and then simultaneously dropwise adding B, C and D solution for t 3 Preserving heat t after the end of dripping 4 And finally, regulating the pH value of the reaction product to n to obtain the polycarboxylate water reducer.
In one embodiment of the method of preparation, the room temperature is 25 ℃ to 28 ℃.
In a preferred embodiment of the method of preparation, the room temperature is 25 ℃.
In one embodiment of the preparation process, t 3 Is 2 to 4 hours, t 4 1 to 2 hours, and n is 6.0 to 8.0.
In one embodiment of the preparation method, 150-200 parts of polyether monomer, 1-5 parts of ester monomer, 10-30 parts of unsaturated acid, 1-5 parts of hydroxycarboxylic acid ester, 1-5 parts of oxidant, 2-10 parts of reducing agent, 0.5-2 parts of chain transfer agent and 300-350 parts of deionized water.
In a preferred embodiment of the method of preparation, the deionized water dissolving the reducing agent is 30-50 parts, the deionized water dissolving the unsaturated acid and the hydroxy carboxylic ester is 10-20 parts, the deionized water dissolving the chain transfer agent is 30-50 parts, and the balance of the deionized water is mixed with the polyether monomer, the ester monomer, and the initiator.
In one embodiment of the preparation method, the reducing agent is one of L-ascorbic acid, sodium hypophosphite and sodium formaldehyde sulfoxylate.
In one embodiment of the method, the initiator is one of hydrogen peroxide, sodium persulfate, or ammonium persulfate.
In one embodiment of the method, the chain transfer agent is one of thioglycolic acid, mercaptopropionic acid, or mercaptoethanol
In one embodiment of the preparation process, the pH of the reaction product is adjusted using a liquid base.
In a preferred embodiment of the preparation method, the liquid-alkali mass fraction is 30% -32%.
Based on the above, compared with the prior art, the ester monomer prepared by the invention has higher reaction activity after the hydroxyl groups at two ends of the polyol are esterified and activated, and more active sites can be provided in the synthesis process of the polycarboxylic acid water reducer, so that the synthesized polycarboxylic acid water reducer has better dispersion performance and working performance. The ester monomer structure contains an ethoxy structural unit, a propoxy structural unit and other alkoxy structural units, so that the ester monomer has better water reducing performance and slump retaining performance. The methacrylate double bond of the terminal group has an in-situ crosslinking effect, and the terminal group participates in the synthesis of the polycarboxylate superplasticizer, so that the biological toxicity is low and the environmental protection is good. The steric hindrance effect of the alkoxy blocks such as ethylene oxide, propylene oxide and the like in the ester monomers can provide dispersion performance for the polycarboxylate water reducer in the synthesis process of the polycarboxylate water reducer.
The ester monomer prepared by the invention adopts polyol to react with hydroxyl and carboxyl to generate the ester monomer by utilizing the easy ring opening effect of the epoxy monomer, and compared with the traditional esterification reaction, the reaction condition is mild, the esterification rate is higher, the generated ester monomer has higher ester group content, and the polycarboxylate water reducer which participates in synthesis can hydrolyze more ester groups, so that the slow release effect is better, and the slump retaining effect is stronger.
The hydroxy carboxylic ester used in the invention contains carbonyl and hydroxyl, has higher polymerization activity, can generate stronger volume steric hindrance effect between carbonyl and hydroxyl, has higher activity density, and can effectively delay the setting time of cement and the like by the water reducer participating in synthesis, so that the synthesized polycarboxylic acid water reducer has better slump retaining performance. In the invention, the environment for synthesizing the polycarboxylate water reducer is an acidic environment, and the hydroxy carboxylate is hydrolyzed into more carboxyl groups than the reaction in an alkaline environment, so that the slump retaining effect is better.
The polycarboxylate water reducer prepared by the invention has the advantages that the ester group is introduced in a copolyester monomer mode, so that the carboxyl content is not reduced due to esterification, the polymerization activity is good, the water reducing and slump retaining effects are excellent, the biotoxicity is low, and the environmental protection performance is good.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments; the technical features designed in the different embodiments of the invention described below can be combined with each other as long as they do not conflict with each other; all other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs and are not to be construed as limiting the present invention; it will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The present invention provides the following examples and comparative examples:
example 1
Weighing 3 parts of ethylene glycol, 6 parts of ethylene oxide and 1 part of hydroquinone, putting into a first reaction device provided with stirring, condensation and temperature control, and uniformly stirring; 1 part of N, N-dimethylaniline and 9 parts of acrylic acid were weighed into a first dropping device. And (3) starting to dropwise add the solution of the first dropwise adding device at the temperature of 80 ℃ for 1h, keeping the temperature of 80 ℃ for 3h after the dropwise adding is finished, ending when the acid value is 5mg KOH/g, and cooling to the room temperature.
Dissolving 2 parts of L-ascorbic acid in 30 parts of deionized water, and placing in a second dripping device; 10 parts of acrylic acid and 1 part of a hydroxycarboxylic acid ester containing a double bond (R 1 ＝2,R 2 =2, containing one double bond) was dissolved in 10 parts deionized water and placed in a third dropping device; dissolving 0.5 part of mercaptoacetic acid in 30 parts of deionized water and placing in a fourth dropping device; 150 parts of TPEG-2400, 1 part of ester monomer, 1 part of hydrogen peroxide and 230 parts of deionized water are mixed together, stirred uniformly, placed into a second reaction device, and simultaneously added with the solutions in the second, third and fourth adding devices dropwise for 2 hours, and then kept at the end of the adding for 1.5 hours. And after the reaction is finished, regulating the pH value of the reaction product to 7.0 by using 30 to 32 mass percent liquid alkali to obtain the polycarboxylate water reducer.
Example 2
Weighing 5 parts of glycerol, 10 parts of propylene oxide and 2 parts of p-hydroxyanisole, putting into a first reaction device provided with stirring, condensation and temperature control, and uniformly stirring; 3 parts of tetraethylammonium bromide and 15 parts of methacrylic acid were weighed into a first dropping device. And (3) starting to dropwise add the solution of the first dropwise adding device at the temperature of 100 ℃ for 1.5h, keeping the temperature of 100 ℃ for 3.5h after the dropwise adding is finished, ending when the acid value is 5.5mg KOH/g, and cooling to the room temperature.
Dissolving 5 parts of sodium hypophosphite in 40 parts of deionized water, and placing the solution in a second dripping device; 15 parts of methacrylic acid and 2 parts of a hydroxycarboxylic acid ester containing a double bond (R 1 ＝3,R 2 =4, containing one double bond) was dissolved in 15 parts deionized water and placed in a third dropping device; dissolving 1 part of mercaptopropionic acid in 40 parts of deionized water and placing in a fourth dripping device; 160 parts of HPEG-2400, 3 parts of ester monomer,Mixing 3 parts of ammonium persulfate with 255 parts of deionized water, uniformly stirring, putting into a second reaction device, dropwise adding the solutions in the second, third and fourth dropwise adding devices for 3 hours, and preserving heat for 2 hours after the dropwise adding is finished. And after the reaction is finished, regulating the pH value of the reaction product to 6.0 by using 30 to 32 mass percent liquid alkali to obtain the polycarboxylate water reducer.
Example 3
Weighing 4 parts of trimethylolpropane, 8 parts of epichlorohydrin and 2 parts of tetramethylpiperidine nitrogen oxide, putting into a first reaction device provided with stirring, condensation and temperature control, and uniformly stirring; 1.5 parts of dimethylformamide and 12 parts of methacrylic acid were weighed into a first dropping device. And (3) starting to dropwise add the solution of the first dropwise adding device at the temperature of 120 ℃ for 2 hours, keeping the temperature of 100 ℃ for 4 hours after the dropwise adding is finished, ending when the acid value is 5mg KOH/g, and cooling to the room temperature.
Dissolving 8 parts of sodium formaldehyde sulfoxylate in 50 parts of deionized water, and placing the solution in a second dropping device; 30 parts of methacrylic acid and 4 parts of a hydroxycarboxylic acid ester containing a double bond (R 1 ＝4,R 2 =6, containing one double bond) was dissolved in 15 parts deionized water and placed in a third dropping device; dissolving 1.5 parts of mercaptopropanol in 45 parts of deionized water and placing the solution in a fourth dropping device; 200 parts of EPEG-3600, 4 parts of ester monomer, 2 parts of sodium persulfate and 240 parts of deionized water are mixed together, stirred uniformly, placed into a second reaction device, and simultaneously added with the solutions in the second, third and fourth adding devices dropwise for 3.5 hours, and kept warm for 2 hours after the addition is finished. And after the reaction is finished, regulating the pH value of the reaction product to 7.5 by using 30 to 32 mass percent liquid alkali to obtain the polycarboxylate water reducer.
Example 4
Weighing 4 parts of sorbitol, 8 parts of epichlorohydrin and 2 parts of hydroquinone, putting into a first reaction device provided with stirring, condensation and temperature control, and uniformly stirring; 1.5 parts of boron trichloride diethyl ether-stannic chloride and 12 parts of acrylic acid are weighed into a first dropping device. And (3) starting to dropwise add the solution of the first dropwise adding device at the temperature of 115 ℃ for 1.5h, keeping the temperature of 115 ℃ for 5h after the dropwise adding is finished, ending when the acid value is 6mg KOH/g, and cooling to the room temperature.
10 parts of armorDissolving sodium aldehyde bisulfate in 40 parts of deionized water, and placing in a second dripping device; 15 parts of acrylic acid and 5 parts of hydroxycarboxylic acid esters containing double bonds (R 1 ＝2,R 2 =2, containing one double bond) was dissolved in 20 parts deionized water and placed in a third dropping device; dissolving 2 parts of mercaptoacetic acid in 50 parts of deionized water and placing in a fourth dripping device; 200 parts of EPEG-5000, 5 parts of ester monomers, 1.5 parts of ammonium persulfate and 210 parts of deionized water are mixed together, stirred uniformly, placed into a second reaction device, and simultaneously added with the solutions in the second, third and fourth adding devices dropwise for 4 hours, and then kept at the end of the adding for 1.5 hours. And after the reaction is finished, regulating the pH value of the reaction product to 8.0 by using 30 to 32 mass percent liquid alkali to obtain the polycarboxylate water reducer.
Comparative example 1
Comparative example 1 differs from example 1 in that polyethylene glycol diacrylate was used instead of the ester monomer in example 1.
Comparative example 2
Comparative example 2 differs from example 1 in that hydroxyethyl acrylate was used instead of the double bond containing hydroxycarboxylic acid ester of example 1.
Comparative example 3
Comparative example 3 differs from example 1 in that the ester monomer was 6 parts and the water was 295 parts.
Comparative example 4
Comparative example 4 differs from example 1 in that the ester monomer was 0.5 parts and the water was 300.5 parts.
Comparative example 5
Comparative example 5 differs from example 1 in that the hydroxycarboxylic acid ester containing a double bond is 0.5 parts and the part of water is 300.5 parts.
Comparative example 6
Comparative example 6 differs from example 1 in that the hydroxycarboxylic acid ester containing a double bond is 6 parts and the part of water is 295 parts.
The above preparation methods, the brands of the raw materials and other technical indexes adopted in the examples and comparative examples can be selected according to the prior art, and if the technical indexes are specified in the invention, the technical indexes are selected within the specified range of the invention, so that the technical effects of the invention are not affected.
The water reducing rate, slump and time slump loss of the concrete are measured according to GB 8076-2008 concrete admixture by adopting standard cement with the mixing amount of 0.20 percent (folded into solid matters) according to the mass of the cement. The concrete mixing ratio is as follows: 360kg/m of cement 3 790kg/m sand 3 Stone 1060kg/m 3 The results obtained are shown in Table 1.
TABLE 1
In summary, the performance of the examples is superior to that of the comparative example, and in comparative example 1, the water reduction rate and slump and expansion for 0h,1h, and 2h of comparative example 1 are smaller than those of example 1, because the polyethylene glycol diacrylate of comparative example 1 does not contain polyhydroxy structure, and the water reduction performance and slump retention performance are reduced; the hydroxyethyl acrylate of comparative example 2 does not contain alpha hydrogen, the reactivity is reduced, the conversion rate of the polycarboxylic acid water reducer participating in synthesis is reduced, the water reducing performance and slump retaining performance are reduced, when the ester monomer of comparative example 3 is too much, the viscosity of cement is too high due to too much released ester group and hydroxyl group, and when the ester monomer of comparative example 4 is too little, the water reducing performance and slump retaining performance are reduced due to insufficient released ester group and hydroxyl group; too little hydroxycarboxylic acid ester containing a double bond in comparative example 5, insufficient ester groups and hydroxy groups are released, too much hydroxycarboxylic acid ester containing a double bond in comparative example 6, excessive ester groups and hydroxy groups are released, and the cement viscosity is too high, which results in deterioration of water-reducing performance and slump retaining performance.
In conclusion, compared with the prior art, after the hydroxyl groups at the two ends of the polyol are esterified and activated, the prepared ester monomer has higher reaction activity, and more active sites can be provided in the synthesis process of the polycarboxylate superplasticizer, so that the polycarboxylate superplasticizer synthesized by the ester monomer has better dispersion performance and working performance. The ester monomer structure contains ethoxy structural units, propoxy structural units and other alkoxy structural units, and the structural units contain polyhydroxy structures, so that the alkoxy structural units of the polycarboxylate water reducer which participates in synthesis are more and hydroxyl structures are introduced, and therefore, the polycarboxylate water reducer has better water reducing performance and slump retaining performance. The methacrylate double bond of the terminal group has an in-situ crosslinking effect, and the terminal group participates in the synthesis of the polycarboxylate superplasticizer, so that the biological toxicity is low and the environmental protection is good. The steric hindrance effect of the alkoxy blocks such as ethylene oxide, propylene oxide and the like in the ester monomers can provide dispersion performance for the polycarboxylate water reducer in the synthesis process of the polycarboxylate water reducer.
The ester monomer prepared by the invention adopts polyol to react with hydroxyl and carboxyl to generate the ester monomer by utilizing the easy ring opening effect of the epoxy monomer, and compared with the traditional esterification reaction, the reaction condition is mild, the esterification rate is higher, the generated ester monomer has higher ester group content, and the polycarboxylate water reducer which participates in synthesis can hydrolyze more ester groups, so that the slow release effect is better, and the slump retaining effect is stronger.
The hydroxyl carboxylic ester used in the invention contains carbonyl and hydroxyl, has higher polymerization activity, can generate stronger volume steric hindrance effect between carbonyl and hydroxyl, has higher activity density, increases the conversion rate of the synthesized polycarboxylate superplasticizer due to the increase of the reactivity due to the alpha hydrogen, and can effectively delay the setting time of cement and the like due to the participation of the synthesized polycarboxylate superplasticizer, so that the synthesized polycarboxylate superplasticizer has better slump retaining performance. In the invention, the environment for synthesizing the polycarboxylate water reducer is an acidic environment, and the hydroxy carboxylate is hydrolyzed into more carboxyl groups than the reaction in an alkaline environment, so that the slump retaining effect is better.
The polycarboxylate water reducer prepared by the invention has the advantages that the ester group is introduced in a copolyester monomer mode, so that the carboxyl content is not reduced due to esterification, the polymerization activity is good, the water reducing and slump retaining effects are excellent, the biotoxicity is low, and the environmental protection performance is good.
In addition, it should be understood by those skilled in the art that although many problems exist in the prior art, each embodiment or technical solution of the present invention may be modified in only one or several respects, without having to solve all technical problems listed in the prior art or the background art at the same time. Those skilled in the art will understand that nothing in one claim should be taken as a limitation on that claim.
Although terms such as ester monomers, polyols, epoxy monomers, unsaturated acids, polyether monomers, hydroxycarboxylic esters, and the like are more used herein, the possibility of using other terms is not precluded. These terms are used merely for convenience in describing and explaining the nature of the invention; they are to be interpreted as any additional limitation that is not inconsistent with the spirit of the present invention; the terms first, second, and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims (8)

1. An ester monomer, characterized in that: is produced by the reaction of reactants including a polyol, an epoxy monomer and an unsaturated acid, wherein the epoxy monomer is one of ethylene oxide, epichlorohydrin, propylene oxide or epoxyhexane, the unsaturated acid is acrylic acid or methacrylic acid, and the polyol is: epoxy monomer: the mass ratio of unsaturated acid is 3-5: 6-10: 9-15 parts of polyhydric alcohol which is one of glycol, glycerol, glucose and sorbitol, 3-5 parts of polyhydric alcohol, 6-10 parts of epoxy monomer and 9-15 parts of unsaturated acid.
2. A process for the preparation of an ester monomer according to claim 1, characterized in that: weighing a catalyst and the unsaturated acid to prepare a solution A; weighing the polyol, the epoxy monomer and the polymerization inhibitor and stirringUniformly stirring at the temperature of T 1 The solution A is added dropwise at the beginning, and the adding time is t 1 After the dripping is finished, at T 2 Constant temperature t at temperature 2 Ending until the acid value is M, and cooling to room temperature;
T 1 at 80-120 ℃, T 2 At 80-120 deg.C t 1 1 to 2 hours, t 2 3 to 5 hours, and M is 6 to 10mg KOH/g.
3. A polycarboxylate water reducing agent, which is characterized in that: resulting from the radical polymerization of an ester monomer according to claim 1, a polyether monomer, an unsaturated acid and a hydroxy carboxylic ester containing a double bond, said ester monomer: the polyether monomer: the unsaturated acid: the mass ratio of the hydroxy carboxylic ester containing double bonds is 1-5:150-200:10-30:1-5.
4. A polycarboxylate water reducing agent according to claim 3, characterized in that: 150-200 parts of polyether monomer, 1-5 parts of ester monomer, 10-30 parts of unsaturated acid and 1-5 parts of hydroxy carboxylic ester.
5. A polycarboxylate water reducing agent according to claim 3, characterized in that: the unsaturated acid is methacrylic acid or acrylic acid, the polyether monomer is one of methyl allyl polyoxyethylene ether, isopentenyl alcohol polyoxyethylene ether or ethylene glycol monovinyl polyethylene glycol ether, and the molecular weight of the polyether monomer is 1200-5000.
6. A polycarboxylate water reducing agent according to claim 3, characterized in that: the structural formula of the double bond-containing hydroxycarboxylic acid ester is as follows:
R 1 is alkenyl with 2-4 carbon atoms, R 2 Is an alkyl group having 1 to 6 carbon atoms.
7. A method for preparing a polycarboxylate superplasticizer according to any one of claims 3 to 6, characterized in that it comprises the following steps: dissolving a reducing agent in deionized water to obtain a solution B; dissolving unsaturated acid and the hydroxy carboxylic ester containing double bonds in deionized water to obtain a solution C; dissolving a chain transfer agent in deionized water to obtain a solution D; mixing the polyether monomer, the ester monomer and the initiator with deionized water, uniformly stirring at room temperature, and then simultaneously dropwise adding B, C and D solution for t 3 Preserving heat t after the end of dripping 4 Finally, regulating the pH value of the reaction product to n to obtain the polycarboxylate water reducer;
t 3 is 2 to 4 hours, t 4 1 to 2 hours, and n is 6.0 to 8.0.
8. The method for preparing the polycarboxylate superplasticizer according to claim 7, wherein: the reducing agent is one of L-ascorbic acid, sodium hypophosphite and formaldehyde sodium bisulfate, the initiator is one of hydrogen peroxide, sodium persulfate or ammonium persulfate, the chain transfer agent is one of thioglycollic acid, mercaptopropionic acid or mercaptoethanol, pH of a reaction product is adjusted by adopting liquid alkali, and the mass fraction of the liquid alkali is 30% -32%.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992010266A1 (en) * 1990-12-04 1992-06-25 Henkel Kommanditgesellschaft Auf Aktien Use of ester-polyol-containing reaction mixtures as foam-inhibiting additives
US6153788A (en) * 1997-08-26 2000-11-28 Bayer Aktiengesellschaft Process for preparing esters of ethylenically unsaturated carboxylic acids
CN102887979A (en) * 2012-10-22 2013-01-23 北京工业大学 Preparation method of star polycarboxylic acid high-performance water reducing agent

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992010266A1 (en) * 1990-12-04 1992-06-25 Henkel Kommanditgesellschaft Auf Aktien Use of ester-polyol-containing reaction mixtures as foam-inhibiting additives
US6153788A (en) * 1997-08-26 2000-11-28 Bayer Aktiengesellschaft Process for preparing esters of ethylenically unsaturated carboxylic acids
CN102887979A (en) * 2012-10-22 2013-01-23 北京工业大学 Preparation method of star polycarboxylic acid high-performance water reducing agent

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