CN111875754A - Polycarboxylate superplasticizer with excellent water reducing property and preparation method thereof - Google Patents
Polycarboxylate superplasticizer with excellent water reducing property and preparation method thereof Download PDFInfo
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- CN111875754A CN111875754A CN202010883362.5A CN202010883362A CN111875754A CN 111875754 A CN111875754 A CN 111875754A CN 202010883362 A CN202010883362 A CN 202010883362A CN 111875754 A CN111875754 A CN 111875754A
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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
- 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
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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
- C04B24/16—Sulfur-containing compounds
- C04B24/161—Macromolecular compounds comprising sulfonate or sulfate groups
- C04B24/163—Macromolecular compounds comprising sulfonate or sulfate groups obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/165—Macromolecular compounds comprising sulfonate or sulfate groups obtained by reactions only involving carbon-to-carbon unsaturated bonds containing polyether side chains
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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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Abstract
A polycarboxylic acid water reducing agent with excellent water reducing property and a preparation method thereof are disclosed, which is polymerized by the following monomers: the monomer A is unsaturated polyether, the monomer B is a polyalcohol polymer with a terminal group containing maleic anhydride, and the monomer C is unsaturated carboxylic acid; the monomer D is 2-ethyl sodium sulfonate containing methacrylic acid; wherein the molecular weight of the monomer A is 2000-5000, and the molecular weight of the monomer B is 1000-4000. The polycarboxylic acid water reducing agent obtained by adjusting the types of the polymerization monomers improves the content of carboxylic acid groups, and greatly improves the water reducing performance of the polycarboxylic acid water reducing agent by cooperating with the steric hindrance of two long side chains.
Description
Technical Field
The invention belongs to the field of water reducing agents, and particularly relates to a polycarboxylic acid water reducing agent with excellent water reducing property 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 concrete. The water reducing agent is added into the concrete mixture to disperse cement particles, and the water reducing agent also has the effects of improving the workability of cement, reducing unit water consumption, improving the fluidity of the concrete mixture and the like.
The polycarboxylate superplasticizer comprises a negatively charged hydrophilic group and a hydrophobic long chain. When the polycarboxylic acid water reducing agent is added into a cement dispersion system, a double electric layer is formed on the surface of cement particles by hydrophilic groups, and the double electric layer generates electrostatic repulsion force to play a role in dispersion; one end of the hydrophobic chain is adsorbed on the surface of cement particles to generate steric hindrance effect, thereby playing a role in reducing water. The polycarboxylate superplasticizer serving as a third-generation concrete superplasticizer has the advantages of high water reducing rate, low mixing amount, large freedom degree of molecular structure design, good dispersibility, good slump loss resistance, wide application range, environmental friendliness and the like, and is a research hotspot and development trend in the field of concrete admixtures at the present stage.
At present, polyether macromonomers such as Methoxy Polyoxyethylene Ether (MPEG), allyl Alcohol Polyoxyethylene Ether (APEG), methyl allyl alcohol polyoxyethylene ether (HPEG) and 4-hydroxybutyl Vinyl Polyoxyethylene Ether (VPEG) are commonly used as polycarboxylic acid water reducing agents. However, the water reducing performance of the existing polycarboxylic acid water reducing agent still needs to be improved, and how to improve the water reducing performance is also a research hotspot of researchers at present.
CN109400822A discloses a method for preparing slump-retaining polycarboxylate superplasticizer mother liquor, which comprises the steps of carrying out water-phase free radical polymerization on unsaturated macromonomers and unsaturated acid under the action of an initiator, a reducing agent and a chain transfer agent, and then adding a byproduct epoxy compound in the industrial production process of an organosilane coupling agent for carrying out epoxy ring-opening esterification reaction to obtain the slump-retaining polycarboxylate superplasticizer mother liquor; the slump retaining performance of the polycarboxylic acid is improved by adjusting the length and the density of a side chain of the polycarboxylic acid water reducing agent; however, the water reducing performance of the polycarboxylic acid water reducing agent obtained by the method is not good and still needs to be improved.
CN109970927A discloses a polycarboxylic acid water reducing agent with excellent early strength performance and slump retaining performance, wherein a long side chain is introduced into a molecule of the polycarboxylic acid water reducing agent through free radical polymerization, active groups such as carboxyl, sulfonic group, ester group, phosphate group, amide group and the like are grafted on a main chain, and all the groups have synergistic action, so that the water reducing performance, the slump retaining performance and the early strength of the polycarboxylic acid water reducing agent are improved, but the water reducing performance improving effect is poor.
CN105236803B discloses a novel polycarboxylate water reducer and a preparation method thereof, the polycarboxylate water reducer is prepared from a polyalkoxy alkenyl long-chain unsaturated monomer, unsaturated carboxylic acid, a chain transfer agent, an oxidant, a reducing agent, water and a micro-crosslinking agent, and the obtained polycarboxylate water reducer can effectively reduce the loss of slump with time, but has a limited water-reducing performance improvement effect.
The polycarboxylate water reducer disclosed in CN109575198A introduces amino groups and silane components capable of promoting cement hydration into molecules, so that the polycarboxylate water reducer acts on cement active components from the beginning of adding the water reducer in the application process, the hydration speed of the cement active components is promoted, the hydration degree of the cement active components is improved, and the early strength and the later strength of concrete are improved; but the water reducing performance of the polycarboxylate superplasticizer is not effectively improved.
Disclosure of Invention
Based on the above, the invention provides a polycarboxylic acid water reducing agent with excellent water reducing property, which comprises the following contents:
a polycarboxylic acid water reducing agent having excellent water reducing properties, said water reducing agent comprising monomers copolymerized to form:
the monomer A is unsaturated polyether, wherein the molecular weight of the monomer A is 2000-5000;
the monomer B is a polyalcohol polymer with an end group containing maleic anhydride, wherein the molecular weight of the monomer B is 1000-4000;
the monomer C is unsaturated carboxylic acid;
the monomer D is 2-ethyl sodium methacrylate.
The polycarboxylic acid water reducing agent of the present invention has improved water reducing property by adjusting the kind of the polymerization monomer. The applicant unexpectedly found that the water reducing agent obtained by adding the monomer D sodium 2-ethanesulfonate methacrylate in the polymerization reaction and copolymerizing the monomer D sodium 2-ethanesulfonate with the three monomers A, B and C has an unexpected improvement effect on the water reducing performance. The Applicant speculates that this is related to the narrow molecular weight distribution, the uniform distribution of the long side chains and the carboxyl groups and the density of the copolymers obtained.
The polycarboxylic acid water reducing agent with excellent water reducing property according to the invention is preferably that the molecular weight of the monomer A is 3000-4000; the molecular weight of the monomer B is 1000-2000.
According to the polycarboxylic acid water reducing agent having excellent water reducing property of the present invention, preferably, the monomer A: a monomer B: a monomer C: the molar ratio of the monomer D is 2-10:2-5:5-15: 1-3. More preferably, the monomer a: a monomer B: a monomer C: the molar ratio of the monomer D is 5-8:3-4:5-10: 2-3. According to one embodiment of the invention, the monomer a: a monomer B: a monomer C: the molar ratio of monomer D was 6:3:6: 2.
According to the polycarboxylic acid water reducing agent with excellent water reducing property, preferably, the unsaturated polyether is at least one selected from ethylene glycol monovinyl polyoxyethylene ether, allyl polyoxyethylene ether and methyl propenyl polyoxyethylene ether, more preferably, the unsaturated polyether is ethylene glycol monovinyl polyoxyethylene ether; the polyol polymer with the terminal group containing maleic anhydride is at least one selected from maleic anhydride polyethylene glycol ester, maleic anhydride polypropylene glycol ester and maleic anhydride polybutylene glycol ester, and more preferably, the polyol polymer with the terminal group containing maleic anhydride is maleic anhydride polyethylene glycol ester; the unsaturated carboxylic acid is selected from (meth) acrylic acid, more preferably the unsaturated carboxylic acid is acrylic acid.
The polycarboxylate superplasticizer with excellent water reducing performance provided by the invention preferably further comprises a monomer E, and the monomer E is styrene. Styrene is used as a polymerization monomer to participate in the polymerization reaction, so that the steric hindrance can be increased, and the water reducing property of the polycarboxylic acid water reducing agent can be further improved by cooperating with the long side chain.
According to the polycarboxylic acid water reducing agent having excellent water reducing property of the present invention, preferably, the monomer A: a monomer B: a monomer C: a monomer D: the molar ratio of the monomer E is 5-8:3-4:5-10:2-3: 0.5-2. More preferably, the monomer a: a monomer B: a monomer C: a monomer D: the molar ratio of monomer E was 6:3:6:2: 0.8.
According to the polycarboxylic acid water reducing agent with excellent water reducing property, the preparation method of the water reducing agent preferably comprises the following steps:
(1) adding a monomer A into an alkaline aqueous solvent, and uniformly stirring to obtain a first solution; adding the monomer B, the monomer C and the monomer D into water, and uniformly stirring to obtain a second solution; adding a reducing agent and a chain transfer agent into water, and uniformly stirring to obtain a third solution;
(2) under the condition of stirring at the constant temperature of 0-30 ℃, firstly adding an initiator into the first solution, then dropwise adding the second solution and the third solution, and preserving heat for 10-90min to obtain a product solution;
(3) and adding alkali liquor into the product solution to adjust the pH value to 6-7, thereby obtaining the polycarboxylic acid water reducing agent.
According to the polycarboxylic acid water reducing agent with excellent water reducing property, preferably, in the step (1), the chain transfer agent is a mixture of isopropanol and mercaptopropanol; wherein the mass ratio of the isopropanol to the mercaptopropanol is 1: 1-3. More preferably, the mass ratio of isopropanol to mercaptopropanol is 1: 2.
According to the polycarboxylic acid water reducing agent with excellent water reducing property, in the step (2), preferably, the initiator is hydrogen peroxide and ferrous sulfate heptahydrate. More preferably, the concentration of hydrogen peroxide is 30 wt%.
In the present invention, the reducing agent is at least one of sodium bisulfite and ascorbic acid, and ascorbic acid is preferable.
According to one embodiment of the invention, the reducing agent is ascorbic acid and the chain transfer agent is a mixture of isopropanol and mercaptopropanol in a mass ratio of 1: 2; wherein the mass ratio of the reducing agent, the chain transfer agent, the hydrogen peroxide and the ferrous sulfate heptahydrate to the monomer A is 0.5-3 wt%, 0.2-2 wt%, 1-5 wt% and 3-10 wt%, respectively; preferably, the mass ratio of the reducing agent, the chain transfer agent, the hydrogen peroxide and the ferrous sulfate heptahydrate to the monomer A is 1-2 wt%, 0.5-1 wt%, 2-3 wt% and 4-5 wt%, respectively. Experiments prove that the molecular weight and the distribution of the generated water reducer can be controlled, the water reducing performance is improved, and the slump retaining performance is improved by controlling the proportion of the reducing agent, the chain transfer agent, the initiator and other compounds within the range.
In addition, the invention also discloses a preparation method for preparing the polycarboxylic acid water reducing agent with excellent water reducing property, which comprises the following steps:
(1) adding a monomer A into an alkaline aqueous solvent, and uniformly stirring to obtain a first solution; adding the monomer B, the monomer C and the monomer D into water, and uniformly stirring to obtain a second solution; adding a reducing agent and a chain transfer agent into water, and uniformly stirring to obtain a third solution;
(2) under the condition of stirring at the constant temperature of 0-30 ℃, firstly adding an initiator into the first solution, then dropwise adding the second solution and the third solution, and preserving heat for 10-90min to obtain a product solution;
(3) adding alkali liquor into the product solution, and adjusting the pH value to 6-7 to obtain a polycarboxylic acid water reducing agent;
wherein:
the monomer A is ethylene glycol monovinyl polyoxyethylene ether, wherein the molecular weight of the monomer A is 3000-4000;
the monomer B is maleic anhydride polyethylene glycol ester, wherein the molecular weight of the monomer B is 1000-2000-;
the monomer C is acrylic acid;
the monomer D is 2-ethyl sodium methacrylate.
According to one embodiment of the invention, the preparation method of the water reducing agent comprises the following steps:
(1) adding sodium phosphate into water to obtain an alkaline aqueous solvent, adding the monomer A into the alkaline aqueous solvent, and uniformly stirring to obtain a first solution; adding the monomer B, the monomer C and the monomer D into water, and uniformly stirring to obtain a second solution; adding a reducing agent and a chain transfer agent into water, and uniformly stirring to obtain a third solution;
(2) under the condition of stirring at the constant temperature of 0-30 ℃, firstly adding an initiator into the first solution, then dropwise adding the second solution and the third solution, and preserving heat for 10-90min to obtain a product solution;
(3) adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 6-7, and obtaining a polycarboxylic acid water reducing agent with the solid content of 30-50 wt%;
wherein the monomer A is ethylene glycol monovinyl polyoxyethylene ether, wherein the molecular weight of the monomer A is 3000-4000;
the monomer B is maleic anhydride polyethylene glycol ester, wherein the molecular weight of the monomer B is 1000-2000-;
the monomer C is acrylic acid;
the monomer D is 2-ethyl sodium methacrylate;
monomer A: a monomer B: a monomer C: the molar ratio of the monomer D is 5-8:3-4:5-10: 2-3;
the reducing agent is ascorbic acid, and the chain transfer agent is a mixture of isopropanol and mercaptopropanol in a mass ratio of 1: 2; wherein the mass ratio of the reducing agent, the chain transfer agent, the hydrogen peroxide and the ferrous sulfate heptahydrate to the monomer A is 0.5-3 wt%, 0.2-2 wt%, 1-5 wt% and 3-10 wt%, respectively; preferably, the mass ratio of the reducing agent, the chain transfer agent, the hydrogen peroxide and the ferrous sulfate heptahydrate to the monomer A is 1-2 wt%, 0.5-1 wt%, 2-3 wt% and 4-5 wt%, respectively; more preferably, in the step (1), a monomer E is further added to the second solution, the monomer E is styrene, and the monomer a: a monomer B: a monomer C: a monomer D: the molar ratio of the monomer E is 5-8:3-4:5-10:2-3: 0.5-2.
Advantageous effects
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the polycarboxylic acid water reducing agent is obtained by adjusting the types of the polymerization monomers, so that the content of carboxylic acid groups is increased, and the water reducing performance of the polycarboxylic acid water reducing agent is greatly improved by cooperating with the steric hindrance of two long side chains; furthermore, sulfonic acid groups are introduced into the side long chains to obviously improve the dispersion property of the water reducer; furthermore, the reinforcing effect and slump retention of the water reducing agent can be synergistically improved by adjusting the types and the contents of the monomers;
as a preferable technical scheme of the invention, the steric hindrance is increased by adding the styrene polymerization monomer, so that the water reducing performance of the water reducing agent is further improved.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the specific embodiments illustrated. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Description of the raw materials
Ethylene glycol monovinyl polyoxyethylene ether with molecular weight of 2000 and 3000, respectively marked as A2000 and A3000; industrial grade.
Maleic anhydride polyethylene glycol esters with molecular weights of 1000, respectively, are designated as B1000; industrial grade.
Acrylic acid; industrial grade.
Sodium 2-ethanesulfonate methacrylate; industrial grade.
Styrene; industrial grade.
Ascorbic acid; industrial grade.
Isopropyl alcohol; industrial grade
3-mercaptopropionic acid; industrial grade.
30 wt% of hydrogen peroxide; industrial grade.
Ferrous sulfate heptahydrate; industrial grade.
Sodium phosphate; industrial grade.
Description of the test methods
Testing of concrete Properties
According to GB8076-2008 'concrete admixture', the concrete base mixing proportion (kg/m)3) Comprises the following steps: m (cement), m (fly ash), m (sand), m (stone), 320:40:800:1050, the slump of the reference concrete is (210 +/-10) mm, the breaking and fixing amount of the fixed water reducing agent is 0.15%, and the water reducing rate, the slump, the expansion and the strength of the concrete are tested. Wherein, the sand used in the test has a fineness modulus of 2.5-3.0 and a mud content of less than 2 wt%; the stone is continuous graded crushed stone with the diameter of 5-20 mm; the cement is flammule P.O42.5R cement; the fly ash is II-grade fly ash; the water reducing agent is a TPEG type common polycarboxylic acid water reducing agent, PCE-1, which is sold in the market.
Molecular weight and distribution test thereof
The molecular weight and the distribution of the water reducing agent are tested by adopting Shimadzu GPC-20A.
Example 1:
(1) adding 1000g of A2000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 500g of B1000, 90g of acrylic acid and 54g of sodium 2-ethanesulfonate methacrylate into 500g of water, and uniformly stirring to obtain a second solution; a mixture of 20g of ascorbic acid and 10g of isopropanol and 3-mercaptopropionic acid in a mass ratio of 1:2 was added to 50g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 40g of ferrous sulfate heptahydrate, stirring for 1min, adding 20g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Example 2:
(1) adding 3000g of A2000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 750g of B1000, 108g of acrylic acid and 108g of sodium 2-ethanesulfonate methacrylate into 500g of water, and uniformly stirring to obtain a second solution; a mixture of 60g of ascorbic acid and 30g of isopropanol and 3-mercaptopropionic acid in a mass ratio of 1:2 was added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 120g of ferrous sulfate heptahydrate, stirring for 1min, adding 60g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Example 3
(1) Adding 3000g of A2000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 750g of B1000, 108g of acrylic acid, 108g of sodium 2-ethanesulfonate methacrylate and 26g of styrene into 500g of water, and uniformly stirring to obtain a second solution; 60g of ascorbic acid and 30g of 3-mercaptopropionic acid were added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 120g of ferrous sulfate heptahydrate, stirring for 1min, adding 60g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Example 4:
(1) adding 3000g of A2000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 750g of B1000, 108g of acrylic acid, 108g of sodium 2-ethanesulfonate methacrylate and 26g of styrene into 500g of water, and uniformly stirring to obtain a second solution; a mixture of 60g of ascorbic acid and 30g of isopropanol and 3-mercaptopropionic acid in a mass ratio of 1:2 was added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 120g of ferrous sulfate heptahydrate, stirring for 1min, adding 60g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Example 5:
(1) adding 3000g of A2000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 750g of B1000, 108g of acrylic acid, 108g of sodium 2-ethanesulfonate methacrylate and 26g of styrene into 500g of water, and uniformly stirring to obtain a second solution; a mixture of 90g of ascorbic acid and 60g of isopropanol and 3-mercaptopropionic acid in a mass ratio of 1:2 was added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 240g of ferrous sulfate heptahydrate, stirring for 1min, adding 150g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Example 6:
(1) adding 3000gA3000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 500g of B1000, 72g of acrylic acid, 72g of sodium 2-ethanesulfonate methacrylate and 18g of styrene into 500g of water, and uniformly stirring to obtain a second solution; a mixture of 60g of ascorbic acid and 30g of isopropanol and 3-mercaptopropionic acid in a mass ratio of 1:2 was added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 120g of ferrous sulfate heptahydrate, stirring for 1min, adding 60g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Comparative example 1:
(1) adding 3000g of A2000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 750g of B1000, 108g of acrylic acid and 58g of hydroxyethyl acrylate into 500g of water, and uniformly stirring to obtain a second solution; 60g of ascorbic acid and 30g of 3-mercaptopropionic acid were added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 120g of ferrous sulfate heptahydrate, stirring for 1min, adding 60g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Comparative example 2:
(1) adding 3000gA3000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 500g of B1000 and 72g of acrylic acid into 500g of water, and uniformly stirring to obtain a second solution; 60g of ascorbic acid and 30g of 3-mercaptopropionic acid were added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 120g of ferrous sulfate heptahydrate, stirring for 1min, adding 60g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Comparative example 3:
(1) adding 3000gA3000, 20g of sodium phosphate and 2000g of water into a four-neck flask with a thermometer, and uniformly stirring to obtain a first solution; adding 108g of acrylic acid and 39g of hydroxyethyl acrylate into 500g of water, and uniformly stirring to obtain a second solution; 60g of ascorbic acid and 30g of 3-mercaptopropionic acid were added to 100g of water and stirred uniformly to form a third solution.
(2) Controlling the temperature of a four-mouth flask at 10 ℃, then adding 120g of ferrous sulfate heptahydrate, stirring for 1min, adding 60g of hydrogen peroxide with the concentration of 30 wt%, and stirring for 5 min; finally, the second solution and the third solution are sequentially dripped into a four-neck flask at the constant temperature of 10 ℃, and the temperature is kept for 30min at 10 ℃ to obtain a product solution.
(3) And adding a sodium hydroxide solution with the mass concentration of 30 wt% into the product solution to adjust the pH value to 7, thereby obtaining the polycarboxylic acid water reducing agent with the solid content of 40 wt%.
Examples of the experiments
The water-reducing agents obtained in examples 1 to 5 and comparative examples 1 to 3 were measured for their molecular weights and their distributions by Shimadzu GPC-20A, respectively, and the results are shown in Table 1:
TABLE 1 molecular weights and distributions of water-reducing agents obtained in examples 1 to 5 and comparative examples 1 to 3
The water reducing agents obtained in examples 1-5 and comparative examples 1-3 are respectively used for preparing concrete grouting material, and the preparation process of the concrete grouting material comprises the following steps: adding 320 parts of flammule P.O42.5R cement, 40 parts of fly ash, 800 parts of sand and 1050 parts of stone into a stirrer, wherein the slump of the standard concrete is (210 +/-10) mm, adding a water reducing agent, fixing the folding and fixing amount of the water reducing agent to be 0.15%, controlling the initial slump of the concrete to be (210 +/-10) mm by adjusting the water consumption, and stirring for 45 minutes to prepare the concrete grouting material.
The performance of the concrete grouting material prepared as described above was tested according to the test method of GB8076-288 "concrete admixture", and the results are shown in table 2:
TABLE 2 Properties of concrete grouting materials prepared in examples 1 to 5 and comparative examples 1 to 3
As can be seen from Table 1, the water-reducing agent of the present invention can increase the number average molecular weight and can obtain a narrower molecular weight distribution by adjusting the kind and ratio of the monomers, as compared with the water-reducing agents prepared in comparative examples 1 to 3. As can be seen from Table 2, the water reducing performance of the water reducing agent can be improved and the mechanical strength of the concrete can be improved by adjusting the types and the proportions of the monomers; the water reducing performance is better for examples 4 and 6 with higher number average molecular weight and narrower molecular weight distribution, which is mainly because the introduction of styrene monomer increases steric hindrance and improves water reducing performance. The broadening of the molecular weight distribution, the decrease of the water reducing property of the water reducing agent and the like, which appear in examples 3 and 5, is caused because the kind and the ratio of materials such as an initiator, a reducing agent and the like added during the polymerization reaction affect the polymerization reaction. Meanwhile, as can be seen from table 2, after styrene is introduced into the polymerization reaction as a monomer, the water reducing performance of the prepared water reducing agent is greatly improved; according to the invention, the concrete prepared from the obtained water reducing agent has good flowing property by adjusting the types and the proportions of the monomers to be within the range limited by the invention.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A polycarboxylic acid water reducing agent having excellent water reducing property, characterized in that said water reducing agent comprises the following monomers copolymerized:
the monomer A is unsaturated polyether, wherein the molecular weight of the monomer A is 2000-5000;
the monomer B is a polyalcohol polymer with an end group containing maleic anhydride, wherein the molecular weight of the monomer B is 1000-4000;
the monomer C is unsaturated carboxylic acid;
the monomer D is 2-ethyl sodium methacrylate.
2. The polycarboxylic acid water reducing agent having excellent water reducing property as claimed in claim 1, wherein the molecular weight of said monomer A is 3000-4000; the molecular weight of the monomer B is 1000-2000.
3. The polycarboxylic acid water reducing agent having excellent water reducing property according to claim 1, wherein the ratio of monomer A: a monomer B: a monomer C: the molar ratio of the monomer D is 2-10:2-5:5-15: 1-3; preferably, the monomer a: a monomer B: a monomer C: the molar ratio of the monomer D is 5-8:3-4:5-10: 2-3.
4. The polycarboxylic acid water reducing agent having excellent water reducing property according to claim 1, wherein said unsaturated polyether is at least one selected from the group consisting of ethylene glycol monovinyl polyoxyethylene ether, allyl polyoxyethylene ether and methacryl polyoxyethylene ether; the polyalcohol polymer with the terminal group containing maleic anhydride is selected from at least one of maleic anhydride polyethylene glycol ester, maleic anhydride polypropylene glycol ester and maleic anhydride polybutylene glycol ester; the unsaturated carboxylic acid is selected from (meth) acrylic acid.
5. The polycarboxylic acid water reducing agent having excellent water reducing property according to any one of claims 1 to 4, characterized in that said water reducing agent further comprises a monomer E, said monomer E being styrene.
6. The polycarboxylic acid water reducing agent having excellent water reducing property according to claim 5, wherein the ratio of monomer A: a monomer B: a monomer C: a monomer D: the molar ratio of the monomer E is 5-8:3-4:5-10:2-3: 0.5-2.
7. The polycarboxylic acid water reducing agent having excellent water reducing property according to claim 1, characterized in that the method for producing the water reducing agent comprises the steps of:
(1) adding a monomer A into an alkaline aqueous solvent, and uniformly stirring to obtain a first solution; adding the monomer B, the monomer C and the monomer D into water, and uniformly stirring to obtain a second solution; adding a reducing agent and a chain transfer agent into water, and uniformly stirring to obtain a third solution;
(2) under the condition of stirring at the constant temperature of 0-30 ℃, firstly adding an initiator into the first solution, then dropwise adding the second solution and the third solution, and preserving heat for 10-90min to obtain a product solution;
(3) and adding alkali liquor into the product solution to adjust the pH value to 6-7, thereby obtaining the polycarboxylic acid water reducing agent.
8. The polycarboxylic acid water reducing agent having excellent water reducing property according to claim 7, wherein in the step (1), the chain transfer agent is a mixture of isopropyl alcohol and mercaptopropanol, wherein the mass ratio of isopropyl alcohol to mercaptopropanol is 1: 1-3.
9. The polycarboxylic acid water reducing agent having excellent water reducing property according to claim 7, wherein in said step (2), the initiator is hydrogen peroxide and ferrous sulfate heptahydrate.
10. A method for preparing a polycarboxylic acid water reducing agent having excellent water reducing property according to any one of claims 1 to 9, characterized by comprising the steps of:
(1) adding a monomer A into an alkaline aqueous solvent, and uniformly stirring to obtain a first solution; adding the monomer B, the monomer C and the monomer D into water, and uniformly stirring to obtain a second solution; adding a reducing agent and a chain transfer agent into water, and uniformly stirring to obtain a third solution;
(2) under the condition of stirring at the constant temperature of 0-30 ℃, firstly adding an initiator into the first solution, then dropwise adding the second solution and the third solution, and preserving heat for 10-90min to obtain a product solution;
(3) adding alkali liquor into the product solution, and adjusting the pH value to 6-7 to obtain a polycarboxylic acid water reducing agent;
wherein:
the monomer A is ethylene glycol monovinyl polyoxyethylene ether, wherein the molecular weight of the monomer A is 3000-4000;
the monomer B is maleic anhydride polyethylene glycol ester, wherein the molecular weight of the monomer B is 1000-2000-;
the monomer C is acrylic acid;
the monomer D is 2-ethyl sodium methacrylate.
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Effective date of registration: 20221215 Address after: 1512 Houxi Avenue, Houxi Town, Jimei District, Xiamen City, Fujian Province, 361000 Patentee after: XIAMEN HONGFA XIANKE NEW BUILDING MATERIALS CO.,LTD. Address before: 101400 room 402, unit 6, building 1, qingqingyuan, Huairou District, Beijing Patentee before: Ma Qingping |