CN111378083A - Polycarboxylic acid dispersant with star structure and preparation method and application thereof - Google Patents
Polycarboxylic acid dispersant with star structure and preparation method and application thereof Download PDFInfo
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- CN111378083A CN111378083A CN201811651470.9A CN201811651470A CN111378083A CN 111378083 A CN111378083 A CN 111378083A CN 201811651470 A CN201811651470 A CN 201811651470A CN 111378083 A CN111378083 A CN 111378083A
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- 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
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- 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
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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
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Abstract
The invention provides a polycarboxylic acid cement dispersant with a star-shaped structure and a preparation method thereof. The star polycarboxylic acid water reducing agent is prepared by polymerizing polyethylene polyamine and epoxide anions to obtain polyether macromonomer with a plurality of amino groups, performing amide/imidization reaction to obtain polymerizable star macromonomer, and performing free radical polymerization with unsaturated acid, unsaturated phosphate and unsaturated macromonomer. The produced product has the advantages of low mixing amount, high water reducing rate, small slump loss, good cement adaptability, obvious reduction of slurry viscosity at low water-cement ratio and the like. The invention adopts free radical polymerization and has the advantages of simple synthesis method, low production process requirement, low production cost, small environmental pollution and the like.
Description
Technical Field
The invention relates to the technical field of concrete additives in building materials, in particular to a star polycarboxylic acid capable of being used as a concrete high-performance water reducing agent and a preparation method thereof.
Background
In recent decades, with the great progress of concrete preparation and construction technology at home and abroad, building structures with super high-rise, large span, high load and the like have made higher requirements on the strength, durability and the like of concrete. The concrete admixture is used as a fifth component indispensable to concrete besides cement, water, gravel aggregate and mineral admixture, and the corresponding demand for the concrete admixture is increasing. The polycarboxylic acid high-performance water reducing agent serving as the most common concrete admixture has the advantages of small mixing amount, high water reducing rate, good slump retaining performance, structural diversity and the like, and plays an important role in improving the fluidity and the workability of concrete, improving the compactness and the durability, controlling the problems of air entraining, retarding, bleeding and the like of the concrete. The excellent dispersing performance of the polycarboxylic acid water reducing agent is derived from a comb-shaped molecular structure, the main chain of the polycarboxylic acid water reducing agent is usually polyacrylic acid or polymethacrylic acid, and polyethylene glycols with different chain lengths are hydrophobic side chains. Through copolymerization with various functional monomers, various functional groups such as carboxyl, sulfonic group, hydroxyl, amino and the like can be introduced into polymer molecules, thereby realizing different macroscopic application performances. Due to incomparable application performance and diversified molecular structures of the polycarboxylic acid water reducing agent, the research on the structure and the performance of the polycarboxylic acid water reducing agent is active, and the polycarboxylic acid water reducing agent is more and more widely applied in recent years.
Under the condition that the structure of the existing monomer is limited, the macroscopic performance of the polycarboxylic acid is difficult to continuously optimize only aiming at the molecular structure of the general polycarboxylic acid. On the other hand, the topological structure distribution of the polycarboxylic acid changes the solution conformation of the polymer, thereby adjusting the macroscopic performance of the copolymer dispersant and providing a new idea for the high performance of the polycarboxylic acid. The researchers of the present invention found that: the segmented polycarboxylic acid is a novel topological structure and is obviously different from the traditional comb-shaped polycarboxylic acid in the aspects of adsorption process and hydration process. (Wang XM, Ran QP, Yang Y, Shu X, Yu C, fluorescence of sequence structure of polycarboxylates on early properties of concept pass, Journal of Materials in Civil Engineering,2016,28(10) 0401611). Star polymers, which are one of the new topological structures, have been the focus and the focus of the scientific research of macromolecules since the past time due to their unique structures and excellent properties.
On the other hand, the improvement of the concrete strength is mainly realized by reducing the water-cement ratio, which also causes the concrete viscosity to be larger, causes a series of construction problems of concrete stirring, transportation, pumping and the like, and limits the popularization and application of high-strength and ultrahigh-strength concrete to a great extent. The viscosity reduction method adopted at present is mainly developed from two aspects of organic additives and admixtures. The added organic additive is mainly an air entraining agent, the air entraining agent is doped to enable a large number of tiny closed spherical bubbles to be formed in the concrete mixture, the microbubbles are the same as the balls, the friction resistance among aggregate particles is reduced, and therefore the viscosity is reduced, but the viscosity reducing effect of the air entraining agent is limited, the introduced bubbles have adverse effects on the strength of high-strength concrete, the action mechanism of the water reducing agent on the viscosity of the concrete is not clear, and the development of the organic viscosity reducing agent is not developed in a breakthrough manner. At present, no relevant patent of concrete organic viscosity reducer appears; the aspect of admixture also does not appear patent or article about concrete viscosity reducer, at present, the working performance of concrete is improved mainly by doping a large amount of fly ash, the viscosity of concrete can be reduced by doping fly ash as is known, but the viscosity reducing effect of high-rise, high-strength or ultrahigh-strength concrete is very limited.
Patent CN105669912B reports that organic molecules of hydroxyl groups of polyols and chain transfer agent containing carboxyl groups react with catalyst to obtain star-shaped RAFT chain transfer agent; then RAFT is carried out on the star polycarboxylic acid water reducer, the unsaturated acid small monomer, the unsaturated large monomer and the initiator to obtain the star polycarboxylic acid water reducer. Patent CN105669913B reports that organic molecules containing polyol hydroxyl group and organic molecules of halogenated acyl halide undergo esterification reaction to obtain multi-terminal halogen radical ATRP initiator; and then carrying out ATRP with an unsaturated acid small monomer, an unsaturated large monomer and a transition metal complex to obtain the star polycarboxylic acid water reducing agent. Both methods belong to controllable free radical polymerization, have harsh reaction conditions, and have the defects of difficult preparation of an initiator, high price, complex post-treatment, colored products and the like.
Patents CN102911322A and CN102887979B report that methacrylic acid and polyol are subjected to esterification reaction under the action of a catalyst to prepare a star-shaped polymerizable active end, and then the star-shaped polymerizable active end is subjected to radical polymerization reaction with an unsaturated polyoxyethylene ether macromonomer, a molecular weight regulator and an unsaturated carboxylic acid monomer under the action of an initiator to prepare the star-shaped polycarboxylic acid water reducer. Most of the polyhydric alcohol in the method exists in a solid form, and the methacrylic acid is liquid, so that the esterification reaction belongs to a heterogeneous reaction, the reaction is difficult, and the esterification rate is low. And the method has the problems of easy formation of crosslinked polymer and uncontrollable reaction.
Patent CN102775089B reports that maleic anhydride and glycerol are subjected to esterification reaction to generate a star-shaped monomer, and then the star-shaped monomer is subjected to free radical polymerization with monomers such as methallyl polyether, acrylic acid, sodium methallyl sulfonate and the like to prepare the star-shaped polycarboxylic acid water reducing agent.
Patent CN105271897B reports that acyl bromination is performed with triethanolamine to obtain a star initiator with bromine as an end group, which initiates hydroxyethyl methacrylate to polymerize to obtain a water reducing agent with a star structure, and because the reactants do not use polyethylene glycol compounds, it is difficult to achieve steric hindrance effect similar to the side chain of the water reducing agent, so that a star polymer is obtained, but the star polymer is not an ideal star polycarboxylic acid water reducing agent structure.
Disclosure of Invention
The invention aims to overcome the problems of insufficient initial dispersing performance of the cement dispersing agent at low water-cement ratio, large early viscosity of concrete and the like, and provides the star polycarboxylic acid high-performance water reducing agent which is easy to obtain raw material sources, low in production cost and simple in production process and the preparation method thereof.
The star-shaped molecular structure of the water reducing agent causes the bulk viscosity and the solution viscosity to be much lower than those of a linear polymer with the same molecular weight. And it has higher chain end functionality, has effectively increased the adsorption drive power with cement granule, has improved the adsorption capacity between it and the cement granule greatly, has increased the steric hindrance effect of molecule to make the water-reducing agent have better dispersion effect. Study in connection with Zhang et al (Effect of superplastic on applied materials with a low water-binder ratio, Journal of materials in Civil Engineering,2016,28(9): 04016085): the viscosity of the concrete at low water-to-gel ratios depends on the residual viscosity in the solution-lower residual viscosities of solutions result in lower concrete viscosities. Thus, the viscosity of concrete doped with the star polycarboxylic acid can be effectively reduced compared with that of the linear polycarboxylic acid at the same doping amount.
The invention provides a polycarboxylic acid dispersant with a star-shaped structure, which is prepared by carrying out anionic polymerization on polyethylene polyamine and epoxide to obtain a polyether macromonomer with a plurality of amino groups, carrying out amide/imidization reaction on the polyether macromonomer with the plurality of amino groups and unsaturated acid to obtain a polymerizable star-shaped macromonomer, and then carrying out free radical polymerization on the polymerizable star-shaped macromonomer, unsaturated acid, unsaturated phosphate and unsaturated macromonomer to obtain the star-shaped polycarboxylic acid water reducer.
The polyethylene polyamine, hereinafter referred to as monomer A, is represented by the general formula ①:
H(NHCH2CH 2)mNH2①
wherein m is an integer of 1 to 4.
The epoxides, referred to below as monomer B, are represented by formula ②:
in the formula R1Is H or CH3，
The unsaturated acid, hereinafter referred to as monomer D, is represented by formula ③:
in the formula R2Is H or CH3；R3Is H or
z is an integer satisfying 0. ltoreq. z.ltoreq.3, when
When present, it can be reacted with COOM1Forming an acid anhydride; m1、M2Is H, alkali metal ion, 1/2 alkaline earth metal ion, ammonium ion or organic amine group;
the unsaturated phosphate ester, hereinafter referred to as monomer F, is represented by formula ④:
in the formula R4Is H or CH3(ii) a n is the number of carbon atoms and is an integer of 2-4; m3Is H, alkali metal ion, 1/2 alkaline earth metal ion, ammonium ion or organic amine group.
The unsaturated macromonomers, hereinafter referred to as monomer G, are represented by the formula ⑤:
in the formula R5Is H or CH3，R6H or alkyl with 1-4 carbon atoms; x is O, CH2O、CH2CH2O, COO, respectively; AO is one or a mixture of two or more of oxyalkylene groups having 2 to 4 carbon atoms, and y is the average molar number of addition of AOAn integer of 5 to 200; when AO in the structural unit of the homopolymer molecule is oxyalkylene with different carbon atom numbers, (AO) y is a random copolymerization or block copolymerization structure;
the monomer A is any one or more of ethylenediamine, diethylenetriamine, triethylene tetramine and tetraethylene pentamine which are mixed in any proportion;
the monomer B is any one or more of ethylene oxide and propylene oxide which are mixed in any proportion;
the monomer D is methacrylic acid, dimethylacrylic acid, acrylic acid, maleic anhydride or itaconic anhydride, but is not limited thereto.
Monomer F can be synthesized according to the prior art in a number of ways: (1) the reaction of phosphoric acid with alcohols at elevated temperatures increases the reaction yield by means of water-carrying agents (US 20080108732). (2) Alcohol phosphorylation method (CN1158132A, US 20090258969).
The preparation method of the monomer F comprises the following steps of reacting unsaturated carboxylic ester with a phosphorylation reagent at 50-120 ℃, preferably 50-90 ℃, wherein the phosphorylation reaction time is 1-6 hours, preferably 2-4 hours, and the structure of the unsaturated carboxylic ester conforms to the general formula ⑥:
the unsaturated carboxylic ester is selected from hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.
The monomer F is one or more of hydroxyethyl methacrylate phosphate, hydroxyethyl acrylate phosphate, hydroxypropyl acrylate phosphate and hydroxypropyl methacrylate phosphate which are mixed in any proportion.
In the present invention, the monomer G represented by formula ⑤ is at least one of the substances having a structure represented by formula ⑤, and is mixed in an arbitrary ratio.
The monomer G represented by the formula ⑤ in the present invention is a polyalkylene glycol mono (meth) acrylate monomer or an unsaturated polyalkylene glycol ether monomer.
When the monomer G represented by the formula ⑤ is a polyalkylene glycol mono (meth) acrylate monomer, it is an esterified product of an alkoxy polyalkylene glycol with (meth) acrylic acid or with (meth) acrylic anhydride, or an adduct of a hydroxyalkyl (meth) acrylate with at least one member selected from the group consisting of ethylene oxide, propylene oxide and butylene oxide, these monomers are used alone or as a mixture of two or more members in an arbitrary ratio, and when AO in the structural unit of the homopolymer molecule is an oxyalkylene group having a different carbon number, (AO) n is a random copolymer or block copolymer structure.
When the monomer G represented by the general formula ⑤ in the present invention is an unsaturated polyalkylene glycol ether-based monomer, it is an adduct of an unsaturated alcohol and at least one of ethylene oxide, propylene oxide and butylene oxide, and these monomers are used alone or as a mixture of two or more thereof in an arbitrary ratio.
The polyalkylene glycol mono (meth) acrylate monomer or the unsaturated polyalkylene glycol ether monomer which may be used as the monomer G is not particularly limited as long as the structural requirement of the general formula ⑤ is satisfied, and the difference in kind thereof has little influence on the properties of the prepared star polycarboxylic acid.
The weight average molecular weight of the star polycarboxylic acid copolymer is 10,000-50,000. If the weight average molecular weight of the star polycarboxylic acid is too small or too large, both water-reducing and slump-retaining properties deteriorate.
The technical principle of the invention is as follows: the star polycarboxylic acid is synthesized by adopting a free radical polymerization method and is applied to the cement dispersing process.
The preparation method of the star polycarboxylic acid cement dispersant provided by the invention comprises the following specific steps:
1) anionic polymerization: uniformly mixing the monomer A and the catalyst a, vacuumizing, slowly heating to 80-150 ℃ under the protection of nitrogen, introducing a certain amount of monomer B, keeping the temperature for 1-2 hours, and cooling to obtain a polyether macromonomer C with multiple amino groups, wherein the molar ratio of the monomer A to the monomer B is as follows: 1:4 to 1:50
The catalyst a is one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, sodium methoxide, potassium tert-butoxide, sodium hydride and metal sodium, and the dosage of the catalyst a is 0.1-2% of the weight of the monomer A.
2) Amide/imidization reaction: heating the polyether macromonomer C with a plurality of amino groups obtained in the step (1) and the monomer D to 60 ℃ under the protection of nitrogen, adding the catalyst b, slowly heating to 80-130 ℃, keeping the temperature for 2-6 hours, and cooling to obtain an acylation product, namely a polymerizable star macromonomer E, wherein the molar ratio of the monomer C to the monomer D is as follows: 1:2 to 1:10
The catalyst b is one or two of 4-dimethylamino pyridine, concentrated sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid and ethylsulfonic acid which are combined in any proportion, and the dosage of the catalyst b is 0.05-10% of the total mass of the monomer C and the monomer D;
3) free radical polymerization: carrying out free radical copolymerization on the acylation product prepared in the step (2), namely polymerizable star macromonomer E, a monomer D, a monomer F and a monomer G in an aqueous medium under the action of an initiator and a chain transfer agent to obtain the polycarboxylic acid dispersant with the star structure;
the molar ratio of the monomer D, the polymerizable star-shaped macromonomer E, the monomer F and the monomer G satisfies the following conditions: G/(D + E + F) is 1/1-1/7, and the monomer D, the monomer E and the monomer F are mixed in any proportion;
the initiator is a conventional free radical water-soluble initiator, one or more of water-soluble hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate can be selected, and the using amount of the initiator is 0.5-5.0 percent of the total weight of the acylation products C, the monomers D and E.
The chain transfer agent is one or more of mercaptoethanol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, isopropanol, hypophosphorous acid, sodium hypophosphite and potassium hypophosphite, and the dosage of the chain transfer agent is 0.5-10.0% of the total weight of the acylation product C, the monomer D and the monomer E.
In the practice of the present invention, the monomer G is added to the reaction vessel before the start of the reaction to thereby increase the conversion and copolymerization activity thereof, and the polymerizable star macromonomer E is added to the reaction vessel in the form of a dropwise addition with the monomer D, the aqueous solution of the monomer F, the aqueous solution of the initiator and the chain transfer agent after the start of the reaction.
When the method is implemented, the higher polymerization concentration is controlled to be 20-60 wt% and the lower polymerization temperature is controlled to be 40-80 ℃ in the step (3), the dropping time of the polymerizable star-shaped macromonomer E, the polymerizable monomer D, the solution of the monomer F and the initiator solution is controlled to be 2-6 hours, and the polymerization reaction time is controlled to be 4-8 hours;
the application method of the star polycarboxylic acid cement dispersant comprises the following steps: the mixing amount is 0.05-1 percent of the total weight of the cementing material,
the application method of the star-shaped polycarboxylic acid cement dispersant is the same as that of the existing water reducing agent, but the addition amount is slightly different. It is generally known to those skilled in the art that there is a certain relationship between the specific amount of water reducing agent and the type of water reducing agent used.
As an improvement, the addition amount of the star polycarboxylic acid cement dispersant is 0.08-0.8%. If the mixing amount is too low, the dispersing effect on cement is unsatisfactory; the mixing amount is too high, which causes economic waste, and the dispersing effect is not further increased.
The star-shaped polycarboxylic acid cement dispersant can also be mixed with at least one water reducing agent selected from sulfamic acid water reducing agents, lignin common water reducing agents and existing polycarboxylate water reducing agents known in the prior art for use. In addition, besides the known water reducing agents for concrete as set forth above, air entraining agents, expanding agents, retarders, early strength agents, tackifiers, shrinkage reducers, defoaming agents, and the like may be added thereto.
Compared with the prior art, the invention has the following advantages:
(1) the method has the advantages of simple synthesis method, low requirement on production process, low production cost and little environmental pollution.
(2) The polycarboxylate superplasticizer prepared by the method has the advantages of low mixing amount, high water reducing rate, small slump loss, good cement adaptability, obvious reduction of slurry viscosity at low water-cement ratio and the like.
Drawings
FIG. 1: comparative example and example 5 are comparative plots of the rheological properties of the neat pastes at low water-to-ash ratios.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following examples.
For a better understanding of the present invention, the present invention will be further described with reference to the following examples.
In the examples of the present invention, the weight average molecular weight Mw of the polymer was measured by miniDAWN Tristar aqueous Gel Permeation Chromatograph (GPC) manufactured by Wyatt technology corporation; the experimental conditions were as follows: column: TSK-GELSW (TOSOH Corp.), eluent: 0.1M NaNO3The flow velocity: 0.8ml/min, injection: 20 μ l of 0.1% aqueous solution (differential refractometer).
Comparative example
30.0g of water was put into a four-neck flask equipped with a stirrer, a thermometer and a dropping device, the temperature was raised to 90 ℃, a mixed monomer solution of 100.0g of polyethylene glycol monomethyl ether methacrylate (Mn 1000g/mol), 18.0g of acrylic acid and 44.0g of water, a mixed solution of 1.8g of ammonium persulfate and 50.0g of water and a mixed solution of 1.21g of sodium bisulfite and 50.0g of water were simultaneously dropped into the reactor, the dropping time was 3 hours, after completion of the dropping, the temperature was kept at that temperature for 2 hours, and 14.3g of 35% NaOH solution was added to neutralize the solution, thereby obtaining a polycarboxylic acid water reducer mother liquor (Mw 24.53 kDa).
Example 1
1) Uniformly mixing 120g of ethylenediamine and 0.12g of sodium hydroxide, vacuumizing, slowly heating to 80 ℃ under the protection of nitrogen, slowly introducing 352g of ethylene oxide, keeping the temperature for 2 hours, and cooling to obtain the polyether macromonomer C with a plurality of amino groups.
2) Heating 14.8g of the polyether macromonomer C with a plurality of amino groups obtained in the step (1) and 19.6g of maleic anhydride to 60 ℃ under the protection of nitrogen, adding 0.02g of p-toluenesulfonic acid, slowly heating to 80 ℃, keeping the temperature for 6 hours, and cooling to obtain an acylation product, namely a polymerizable star macromonomer E.
3) In a glass reactor equipped with a thermometer, a stirrer, a dropping funnel and a nitrogen inlet tube, 200g of polyethylene glycol monomethyl ether acrylate (Mn 500g/mol) was charged, and 133.3g of deionized water was simultaneously charged, and while stirring, the reaction vessel was purged with nitrogen, and the temperature was raised to 40 ℃ and stirred uniformly. Stirring 34.4g of the acylation product prepared in the step (2), namely polymerizable star macromonomer E, 19.6g of maleic anhydride, 19.6g of hydroxyethyl acrylate phosphate, 1.4g of hydrogen peroxide, 1.4g of mercaptoethanol and 49g of water to prepare a uniform monomer aqueous solution, dropwise adding the monomer aqueous solution into a reactor for 6 hours, preserving the temperature for 2 hours after dropwise adding, cooling to room temperature, adding alkali to neutralize to a pH value of 6.8, and obtaining a star-shaped polycarboxylic acid solution with the solid content of 59.8%, wherein the molecular weight Mw is 10.03 kDa.
Example 2
1) Mixing 103g of diethylenetriamine and 0.21g of potassium hydroxide uniformly, vacuumizing, slowly heating to 120 ℃ under the protection of nitrogen, slowly introducing 580g of propylene oxide, keeping the temperature for 1.5h, and cooling to obtain the polyether macromonomer C with a plurality of amino groups.
2) And (2) heating 13.9g of the polyether macromonomer C with multiple amino groups obtained in the step (1) and 17.2g of methacrylic acid to 60 ℃ under the protection of nitrogen, adding 0.03g of benzenesulfonic acid, slowly heating to 110 ℃, keeping the temperature for 4 hours, and cooling to obtain an acylation product, namely the polymerizable star macromonomer E.
3) In a glass reactor equipped with a thermometer, a stirrer, a dropping funnel and a nitrogen inlet tube, 200g of polyethylene glycol monomethyl ether methacrylate (Mn 1000g/mol) was charged, and 300g of deionized water was simultaneously charged, and while stirring, the reaction vessel was purged with nitrogen, and the temperature was raised to 60 ℃ and stirred uniformly. 26.8g of the acylation product prepared in the step (2), namely polymerizable star macromonomer E, 17.2g of methacrylic acid, 39.2g of hydroxyethyl acrylate phosphate, 2.8g of ammonium persulfate, 5.7g of thioglycolic acid and 124.8g of water are stirred to prepare a uniform monomer aqueous solution, the monomer aqueous solution is dropwise added into a reactor for 3 hours, the temperature is kept for reaction for 2 hours after the dropwise addition is finished, the reaction solution is cooled to room temperature, alkali is added to neutralize the solution until the pH value is 6.8, and a star polycarboxylic acid solution with the solid content of 40.2 percent is obtained, wherein the molecular weight of the star polycarboxylic acid solution is Mw 36.26 kDa.
Example 3
1) Mixing 103g of diethylenetriamine and 0.52g of sodium methoxide uniformly, vacuumizing, slowly heating to 100 ℃ under the protection of nitrogen, slowly introducing 1160g of propylene oxide, keeping the temperature for 2 hours, and cooling to obtain the polyether macromonomer C with a plurality of amino groups.
2) And (2) heating 13.9g of the polyether macromonomer C with multiple amino groups obtained in the step (1) and 30g of dimethylacrylic acid to 60 ℃ under the protection of nitrogen, adding 0.44g of concentrated sulfuric acid, slowly heating to 100 ℃, keeping the temperature for 5 hours, and cooling to obtain an acylation product, namely the polymerizable star macromonomer E.
3) In a glass reactor equipped with a thermometer, a stirrer, a dropping funnel and a nitrogen inlet tube, 200g of polyethylene glycol monomethyl ether methacrylate (Mn 2000g/mol) was charged, and 200g of deionized water was simultaneously charged, and while stirring, the reaction vessel was purged with nitrogen, and the temperature was raised to 50 ℃ and stirred uniformly. Stirring 28.9g of the acylation product prepared in the step (2), namely polymerizable star macromonomer E, with 20g of dimethyl acrylic acid, 21g of hydroxyethyl methacrylate phosphate, 5.4g of sodium persulfate, 2.7g of 2-mercaptopropionic acid and 69.8g of water to prepare a uniform monomer aqueous solution, dropwise adding the monomer aqueous solution into a reactor for 5 hours, keeping the temperature for reaction for 2 hours after the dropwise adding is finished, cooling to room temperature, adding alkali to neutralize to a pH value of 6.8, and obtaining a star polycarboxylic acid solution with the solid content of 49.9%, wherein the molecular weight is 47.24 kDa.
Example 4
1) Uniformly mixing 116.8g of triethylene tetramine and 0.93g of potassium methoxide, vacuumizing, slowly heating to 140 ℃ under the protection of nitrogen, slowly introducing 1056g of ethylene oxide, keeping the temperature for 1h, and cooling to obtain the polyether macromonomer C with a plurality of amino groups.
2) Heating 12.9g of polyether macromonomer C with a plurality of amino groups obtained in the step (1) and 23g of acrylic acid to 60 ℃ under the protection of nitrogen, adding 0.72g of 4-dimethylaminopyridine, slowly heating to 90 ℃, keeping the temperature for 5 hours, and cooling to obtain an acylation product, namely polymerizable star macromonomer E.
3) In a glass reactor equipped with a thermometer, a stirrer, a dropping funnel and a nitrogen inlet tube, 240g of butenyl polyoxyethylene ether (Mn 2400g/mol) was charged, and 560g of deionized water was simultaneously charged, and the reaction vessel was purged with nitrogen while stirring, and heated to 80 ℃ and stirred uniformly. Stirring 24.4g of the acylation product prepared in the step (2), namely polymerizable star macromonomer E, with 28.8g of acrylic acid, 21g of hydroxypropyl acrylate phosphate, 9.4g of potassium persulfate, 9.4g of isopropanol and 173.2g of water to prepare a uniform monomer aqueous solution, dropwise adding the monomer aqueous solution into a reactor for 2 hours, preserving the temperature for reaction for 2 hours after the dropwise adding is finished, cooling to room temperature, adding alkali for neutralizing to pH value of 6.8 to obtain a star polycarboxylic acid solution with the solid content of 29.7%, wherein the molecular weight Mw is 31.55 kDa.
Example 5
1) Uniformly mixing 116.8g of triethylene tetramine and 1.17g of potassium tert-butoxide, vacuumizing, slowly heating to 150 ℃ under the protection of nitrogen, slowly introducing 1408g of ethylene oxide, keeping the temperature for 1 hour, and cooling to obtain the polyether macromonomer C with a plurality of amidogens.
2) Heating 12.9g of polyether macromonomer C with a plurality of amino groups obtained in the step (1) and 30.9g of methacrylic acid to 60 ℃ under the protection of nitrogen, adding 2.2g of ethyl sulfonic acid, slowly heating to 120 ℃, keeping the temperature for 3h, and cooling to obtain an acylation product, namely polymerizable star macromonomer E.
3) In a glass reactor equipped with a thermometer, a stirrer, a dropping funnel and a nitrogen inlet tube, 240g of butenyl polyoxyethylene ether (Mn 2400g/mol) was charged, while 360g of deionized water was charged, and the reaction vessel was purged with nitrogen while stirring, and heated to 60 ℃ and stirred uniformly. 26.6g of acylation product prepared in the step (2), namely polymerizable star macromonomer E, 25.8g of methacrylic acid, 11.2g of hydroxyethyl methacrylate phosphate, 12.1g of ammonium persulfate, 15.2g of 3-mercaptopropionic acid and 95.5g of water are stirred to prepare a uniform monomer aqueous solution, the monomer aqueous solution is dropwise added into a reactor for 4 hours, the temperature is kept for reaction for 2 hours after the dropwise addition is finished, the reaction solution is cooled to room temperature, alkali is added to neutralize the reaction solution until the pH value is 6.8, and a star polycarboxylic acid solution with the solid content of 40.1 percent is obtained, wherein the molecular weight Mw is 21.13 kDa.
Example 6
1) 113.4g of tetraethylenepentamine and 2.26g of sodium hydride are uniformly mixed, then the mixture is vacuumized, slowly heated to 130 ℃ under the protection of nitrogen, 1320g of ethylene oxide is slowly introduced, the temperature is kept for 1 hour, and the temperature is reduced to obtain the polyether macromonomer C with a plurality of amino groups.
2) Heating 12.3g of polyether macromonomer C with a plurality of amino groups obtained in the step (1) and 29.4g of maleic anhydride to 60 ℃ under the protection of nitrogen, adding 4.1g of concentrated sulfuric acid, slowly heating to 130 ℃, keeping the temperature for 2 hours, and cooling to obtain an acylation product, namely polymerizable star macromonomer E.
3) In a glass reactor equipped with a thermometer, a stirrer, a dropping funnel and a nitrogen inlet tube, 240g of allyl polyoxyethylene ether (Mn 8000g/mol) was charged, and 960g of deionized water was simultaneously charged, and the reaction vessel was purged with nitrogen while stirring, and heated to 70 ℃ and stirred uniformly. 26.9g of acylation product prepared in the step (2), namely polymerizable star macromonomer E, 11.8g of maleic anhydride, 10.5g of hydroxypropyl methacrylate phosphate, 14.4g of hydrogen peroxide, 28.9g of hypophosphorous acid and 196.9g of water are stirred to prepare a uniform monomer aqueous solution, the monomer aqueous solution is dropwise added into a reactor for 3 hours, the temperature is kept for 2 hours after the dropwise addition, the reaction is cooled to room temperature, alkali is added to neutralize the solution until the pH value is 6.8, and a star polycarboxylic acid solution with the solid content of 20.2 percent is obtained, wherein the molecular weight is 31.65 kDa.
The application example is as follows:
in the application example, the adopted cement is 52.5 PiII of small wild field, P.O 42.5 of sea snail manufactured by Anhui sea snail cement company Limited, P.O 42.5 of Jieching Huishu Jilin cement company Limited, P.O 42.5 of Nanjing Unioncement company Limited, the silica fume is Sampson silica fume manufactured by Shandong Boken silicon material company Limited, the sand is medium sand with the fineness modulus M of 2.6, and the stone is crushed stone with the grain diameter of 5-20 mm in continuous gradation.
The test methods of water reducing rate, bleeding rate, gas content and setting time in the application examples are carried out according to the relevant regulations of GB8077-2012 test method for homogeneity of concrete admixtures.
Application example 1
The influence of the synthesized star polycarboxylic acids of comparative examples and examples on fresh concrete was evaluated, the water-cement ratio was fixed to 0.41, and the amount of polycarboxylic acid solid was adjusted so that the initial slump of fresh concrete was 21 cm. + -. 2cm, and the results of the experiment are shown in Table 1.
TABLE 1 Effect of the Star-shaped polycarboxylic acids synthesized in the comparative examples and examples on fresh concrete Properties
The comb-shaped polycarboxylic acid of the comparative example had an initial slump of 20.7cm at a blending amount of 0.22%, a loss with time of 18.2cm at 30min, an initial spreading of 50cm and a loss with time of 38cm at 30 min. The content of air in concrete is not changed basically when the content of the synthesized star polycarboxylic acid in the example is 0.18% of the cement dosage, and the slump and the expansion degree of the concrete are mostly better than those of the comparative example, such as example 5, the initial slump is 22.5cm, the loss with time of 30min is 20.8cm, the initial expansion degree is 62cm, and the loss with time of 30min is 52.5 cm. Therefore, compared with the traditional comb-shaped polycarboxylic acid, the star-shaped polycarboxylic acid has excellent dispersing performance, high water reducing rate, low mixing amount and small slump loss.
Application example 2
The suitability of the star polycarboxylic acids obtained in comparative example and example 5 for cement was evaluated, the fixed water cement ratio was 0.29, and the results of the net paste fluidity were as shown in Table 2.
TABLE 3 Adaptation of the Star-shaped polycarboxylic acids synthesized in comparative examples and example 5 to different cements
In the small-open-field cement or the sea snail cement, when the same fluidity was achieved, the comparative example was slightly higher in the amount of the star polycarboxylic acid prepared in synthetic example 5 and slightly inferior in the dispersion retention property. In the rhinestone cement or the middle-linked cement, the water reducing and dispersing effects of the comparative example are obviously reduced, the inadaptability of the cement is shown, and the star polycarboxylic acid water reducing agent prepared in the embodiment 5 of the invention has good dispersibility and dispersion retentivity in four kinds of cement, better adaptability and better comprehensive performance. As described above, the star polycarboxylic acid water reducing agent obtained in Synthesis example 5 had good initial dispersibility and good dispersion retention property in any cement, and was satisfactory in suitability for cement.
Application example 3
Evaluation of comparative example and example 5 at Low Water-to-Ash ratio(W/C ═ 0.22) neat paste rheology, adjusted admixture loading to give an initial freeness of fresh slurry of 235 mm. + -.5 mm, using a Brookfield Soft solids test rheometer (R/S-SST) in USA, the test procedure was as follows: the initial 1min is a pre-shearing stage, and the shearing rate is 100s-1"pre-shearing" is intended to destroy the flocculation structure formed in the cement paste; shear rate from 100s-1Down to 0s-1A time of 10s is required, after which shearing is stopped for 1min in order to reduce the preferential shear planes due to the orientation of the cement grains; after which the shear rate was from 0s in 1min-1Increased to 100s-1Then, the temperature is reduced to 0s in the next 1min-1The apparent viscosity takes the last drop in data. The results of the rheological properties of the neat pastes at low water-to-ash ratios for the comparative example and example 5 are shown in FIG. 1.
As can be seen from the rheology curve of the descending section of the freshly mixed pulp slurry, the same shear rate (30.5 s)-1) The shear viscosity of the comparative example is 1.5Pa.s, and the shear viscosity of the example 5 is 0.9Pa.s, so that the viscosity of the fresh slurry of the star polycarboxylic acid water reducing agent prepared by the example 5 of the present invention is obviously reduced under the condition of low water-cement ratio at the same fluidity. Under the condition of the same water-cement ratio (W/C is 0.22), the same extension degree (235 mm) is achieved, the content of star polycarboxylic acid (0.28%) is 0.06% lower than that of comb-type polycarboxylic acid (0.34%), and the star-type polycarboxylic acid has larger water reduction rate than the comb-type polycarboxylic acid, and the slurry has lower apparent viscosity.
Claims (14)
1. A polycarboxylic acid dispersant with a star structure is characterized in that polyethylene polyamine and epoxide are subjected to anionic polymerization to obtain a polyether macromonomer with a plurality of amino groups, the polyether macromonomer with the plurality of amino groups and unsaturated acid are subjected to amide/imide reaction to obtain a polymerizable star macromonomer, and then the polymerizable star macromonomer, the unsaturated acid, unsaturated phosphate and the unsaturated macromonomer are subjected to free radical polymerization to obtain the polycarboxylic acid dispersant;
the polyethylene polyamine, hereinafter referred to as monomer A, is represented by the general formula ①:
H(NHCH2CH2)mNH2①
wherein m is an integer of 1 to 4;
the epoxides, referred to below as monomer B, are represented by formula ②:
in the formula R1Is H or CH3；
The polyether macromonomer with a plurality of amine groups is referred to as a monomer C below;
the unsaturated acid, hereinafter referred to as monomer D, is represented by formula ③:
in the formula R2Is H or CH3；R3Is H or
z is an integer satisfying 0. ltoreq. z.ltoreq.3, when
When present, it can be reacted with COOM1Forming an acid anhydride; m1、M2Is H, alkali metal ion, 1/2 alkaline earth metal ion, ammonium ion or organic amine group;
the unsaturated phosphate ester, hereinafter referred to as monomer F, is represented by formula ④:
in the formula R4Is H or CH3(ii) a n is the number of carbon atoms and is an integer of 2-4; m3Is H, alkali metal ion, 1/2 alkaline earth metal ion, ammonium ion or organic amine group;
the unsaturated macromonomers, hereinafter referred to as monomer G, are represented by the formula ⑤:
in the formula R5Is H or CH3，R6H or alkyl with 1-4 carbon atoms; x is O, CH2O、CH2CH2O, COO, respectively; AO is any one or a mixture of two or more of oxyalkylene groups having 2 to 4 carbon atoms, and y is an average addition mole number of AO and is an integer of 5 to 200; when AO in the structural unit of the homopolymer molecule is an oxyalkylene group having a different carbon number, (AO) y is a random copolymer or a block copolymer.
2. The polycarboxylic acid dispersant with a star structure as claimed in claim 1, wherein said monomer A is one or more selected from ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine, and is mixed in any ratio.
3. The polycarboxylic acid dispersant with a star structure according to claim 1, wherein said monomer B is one or more of ethylene oxide and propylene oxide mixed in any ratio.
4. The polycarboxylic acid dispersant with a star structure according to claim 1, wherein said monomer D is methacrylic acid, dimethylacrylic acid, acrylic acid, maleic anhydride or itaconic anhydride.
5. The polycarboxylic acid dispersant with the star structure as claimed in claim 1, wherein the monomer F is prepared by reacting unsaturated carboxylic acid ester with a phosphorylation reagent at 50-120 ℃, wherein the phosphorylation reaction time is 1-6 h, and the structure of the unsaturated carboxylic acid ester is consistent with a general formula ⑥:
the unsaturated carboxylic ester is selected from hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.
6. The polycarboxylic acid dispersant with the star structure as claimed in claim 5, wherein the reaction temperature for preparing the monomer F is 50-90 ℃ and the reaction time is 2-4 h.
7. The polycarboxylic acid dispersant of star structure according to claim 5 or 6, wherein said monomer F is one or more selected from hydroxyethyl methacrylate phosphate, hydroxyethyl acrylate phosphate, hydroxypropyl acrylate phosphate and hydroxypropyl methacrylate phosphate mixed in any ratio.
8. The polycarboxylic acid dispersant of star structure according to claim 1, wherein monomer G is a polyalkylene glycol mono (meth) acrylate monomer or an unsaturated polyalkylene glycol ether monomer.
9. The polycarboxylic acid dispersant with star structure as claimed in claim 1, wherein said star polycarboxylic acid copolymer has a weight average molecular weight of 10,000 to 50,000.
10. The method for preparing the polycarboxylic acid dispersant with the star structure as set forth in any one of claims 1 to 9, characterized by comprising the following steps:
1) anionic polymerization: uniformly mixing the monomer A and the catalyst a, vacuumizing, slowly heating to 80-150 ℃ under the protection of nitrogen, introducing a certain amount of monomer B, keeping the temperature for 1-2 hours, and cooling to obtain a polyether macromonomer C with multiple amino groups, wherein the molar ratio of the monomer A to the monomer B is as follows: 1: 4-1: 50;
the catalyst a is one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, sodium methoxide, potassium tert-butoxide, sodium hydride and metal sodium, and the dosage of the catalyst a is 0.1-2% of the weight of the monomer A;
2) amide/imidization reaction: heating the polyether macromonomer C with a plurality of amino groups obtained in the step (1) and the monomer D to 60 ℃ under the protection of nitrogen, adding the catalyst b, slowly heating to 80-130 ℃, keeping the temperature for 2-6 hours, and cooling to obtain an acylation product, namely a polymerizable star macromonomer E, wherein the molar ratio of the monomer C to the monomer D is as follows: 1: 2-1: 10;
the catalyst b is one or two of 4-dimethylamino pyridine, concentrated sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid and ethylsulfonic acid which are combined in any proportion, and the dosage of the catalyst b is 0.05-10% of the total mass of the monomer C and the monomer D;
3) free radical polymerization: carrying out free radical copolymerization on the acylation product prepared in the step (2), namely polymerizable star macromonomer E, a monomer D, a monomer F and a monomer G in an aqueous medium under the action of an initiator and a chain transfer agent to obtain the polycarboxylic acid dispersant with the star structure;
the molar ratio of the monomer D, the polymerizable star-shaped macromonomer E, the monomer F and the monomer G satisfies the following conditions: G/(D + E + F) is 1/1-1/7, and the monomer D, the monomer E and the monomer F are mixed in any proportion;
the initiator is a conventional free radical water-soluble initiator, one or more of water-soluble hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate can be selected, and the using amount of the initiator is 0.5-5.0 percent of the total weight of the acylation product C, the monomer D and the monomer E;
the chain transfer agent is one or more of mercaptoethanol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, isopropanol, hypophosphorous acid, sodium hypophosphite and potassium hypophosphite, and the dosage of the chain transfer agent is 0.5-10.0% of the total weight of the acylation product C, the monomer D and the monomer E.
11. The process according to claim 10, wherein the monomer G is added to the reaction vessel before the start of the reaction to thereby increase the conversion and copolymerization activity thereof, and the polymerizable star macromonomer E is added to the reaction vessel in the form of a dropwise addition with the aqueous solution of the monomer D, the aqueous solution of the monomer F, the aqueous solution of the initiator and the chain transfer agent after the start of the reaction.
12. The method as claimed in claim 10, wherein the step (3) is carried out at a lower polymerization temperature of 40-80 ℃, the dropping time of the polymerizable star macromonomer E, the monomer D, the solution of the monomer F and the initiator solution is controlled to be 2-6 h, and the polymerization reaction time is controlled to be 4-8 h.
13. The method of using a polycarboxylic acid dispersant of star structure according to any of claims 1 to 9, characterized in that it is incorporated in an amount ranging from 0.05% to 1% by weight of the total cement.
14. The application method as claimed in claim 10, wherein the content of the polycarboxylic acid dispersant with the star structure is 0.08-0.8%.
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| CN113667067A (en) * | 2020-05-13 | 2021-11-19 | 辽宁奥克化学股份有限公司 | Solid polycarboxylic acid water reducing agent and preparation method thereof |
| CN114736336A (en) * | 2022-04-25 | 2022-07-12 | 华新水泥股份有限公司 | Preparation method of star alcohol amine ester polycarboxylic acid cement grinding aid |
| CN117430760A (en) * | 2023-12-20 | 2024-01-23 | 四川省晋川建材有限公司 | Mud-resistant polycarboxylate superplasticizer and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113667067A (en) * | 2020-05-13 | 2021-11-19 | 辽宁奥克化学股份有限公司 | Solid polycarboxylic acid water reducing agent and preparation method thereof |
| CN113667067B (en) * | 2020-05-13 | 2022-05-17 | 辽宁奥克化学股份有限公司 | Solid polycarboxylic acid water reducing agent and preparation method thereof |
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| CN114736336A (en) * | 2022-04-25 | 2022-07-12 | 华新水泥股份有限公司 | Preparation method of star alcohol amine ester polycarboxylic acid cement grinding aid |
| CN114736336B (en) * | 2022-04-25 | 2023-06-06 | 华新水泥股份有限公司 | Preparation method of star-shaped alcohol amine ester polycarboxylic acid cement grinding aid |
| CN117430760A (en) * | 2023-12-20 | 2024-01-23 | 四川省晋川建材有限公司 | Mud-resistant polycarboxylate superplasticizer and preparation method thereof |
| CN117430760B (en) * | 2023-12-20 | 2024-03-08 | 四川省晋川建材有限公司 | Mud-resistant polycarboxylate superplasticizer and preparation method thereof |
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