CN111349199A - Steady-state polycarboxylic acid superplasticizer with core-shell structure and preparation method thereof - Google Patents
Steady-state polycarboxylic acid superplasticizer with core-shell structure and preparation method thereof Download PDFInfo
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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
- C08F285/00—Macromolecular compounds obtained by polymerising monomers on to preformed graft polymers
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2688—Copolymers containing at least three different monomers
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- C08F2/00—Processes of polymerisation
- C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
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- 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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- 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
The core structure of the stable polycarboxylic acid superplasticizer with the core-shell structure is obtained by emulsion polymerization of a vinyl glycol ether monomer containing a hydrophobic chain segment and a derivative monomer A thereof, an unsaturated carboxylic acid or anhydride monomer B, an alkyl acrylate monomer C and an allyl polyether reactive emulsifier D; the shell structure is obtained by aqueous solution polymerization of a vinyl polyethylene glycol ether monomer and a derivative monomer E thereof, an unsaturated carboxylic acid or anhydride monomer B and a (methyl) acrylic hydroxyl ester unsaturated micromolecule substance F. The stable polycarboxylic acid superplasticizer provided by the invention is simple in preparation method, good in initial dispersibility in engineering use, capable of maintaining concrete fluidity for a long time, capable of remarkably improving concrete workability, and excellent in material adaptability.
Description
Technical Field
The invention belongs to the technical field of concrete admixtures, and particularly relates to a polycarboxylic acid superplasticizer capable of remarkably prolonging the working time of high-performance concrete during application and a preparation method thereof.
Background
The development of the building industry is very rapid in the world, and the construction of super high-rise/complex structure buildings, large bridges, nuclear power, hydropower and other heavy projects puts higher requirements on the quality of high-performance concrete and also brings great challenges. The construction difficulty is gradually increased due to the complexity of the structure and the automation of the construction mode, the fluidity maintaining time of the high-performance concrete is required to be longer, and the fluidity maintaining of the high-performance concrete is difficult due to the large amount of mineral admixtures and multifunctional admixtures. Because the construction temperature, the quality and the property of the concrete raw material in each region are very different, the phenomenon that the flowability of fresh concrete is lost too fast is often encountered in the mixing and transportation processes of the concrete.
The insufficient slump retaining capacity of the concrete brings a lot of problems to engineering construction and the quality of the concrete, and the phenomenon is more obvious particularly under the high-temperature condition in summer when the slump retaining capacity of the concrete is smaller or the requirement of the slump retaining capacity for an ultra-long time is required. Therefore, the stable construction performance of the high-performance concrete under different regional materials and construction environments is very important.
Through the intensive research of a large number of scholars in the field of the professional field, the development and large-scale use of the polycarboxylic acid water reducing agent obviously improve the construction performance of concrete, and the polycarboxylic acid water reducing agent is identified as the most key component of high-performance concrete, and the polycarboxylic acid water reducing agent can be reasonably and effectively used to reduce the using amount of a cementing material, increase the using amount of industrial waste residues and improve the long-term durability.
The reason for the loss of concrete fluidity is that cement hydration products are increased due to cement hydration and water evaporation, and the cement hydration products are increased due to too long concrete construction time, and the phenomenon that the fluidity is gradually lost if the generated hydration products are not dispersed by excessive dispersing agents in a concrete system.
Thus, the nature of the fluidity loss due to different factors varies, as does the time required to replenish the dispersant.
In order to solve the problems, researchers at home and abroad carry out a great deal of improvement work, and the research in the field is focused on polycarboxylic acid series water reducing agents by virtue of excellent comprehensive properties and modifiable molecular structures. The conventional method is characterized in that except for the traditional retarding method, the slump-retaining polycarboxylic acid water reducing agent is adopted for compounding to achieve the purpose of prolonging the construction time of concrete.
Some Chinese patents disclose relevant slump-retaining polycarboxylic acid water reducing agents and preparation methods thereof, and the methods introduce a large amount of ester bonds in the molecular structure of polycarboxylic acid and gradually hydrolyze out adsorption groups under the alkaline catalysis of cement so as to achieve the aim of continuous dispersion. The methods still have the problems of low water reducing performance caused by excessive ester monomers and uneven polymerization caused by insufficient water solubility of the ester monomers, and the like, and also have the problems of waste caused by too high mixing amount or incapability of achieving the purpose of slump retaining performance caused by unreasonable compounding of the water reducing component and the slump retaining component. The molecular design of the slump-retaining type polycarboxylate superplasticizer also has a larger lifting space.
Disclosure of Invention
In order to avoid the problems, the important requirement of the long-time construction performance of the high-performance concrete is met, and the technical support is provided for the concrete with the ultra-long-time slump retaining requirement. The invention provides a stable polycarboxylic acid superplasticizer which has high water reducing capacity and an unrivaled long-time slump retaining effect.
The stable polycarboxylic acid superplasticizer is prepared by firstly preparing a core structure polymer in an aqueous solution by adopting an emulsion polymerization mode and then preparing a shell layer polymer by adopting aqueous solution polymerization. Compared with the conventional polycarboxylic acid molecular structure, the stable polycarboxylic acid superplasticizer has a hydrophilic polymer shell structure, contains strong polar anionic groups and ester groups of hydroxyl ester with good water solubility, and can provide the functions of early and medium fluidity and slump retaining of concrete while providing strong dispersing capacity. Meanwhile, the core polymer with the super-long slump retaining capability is subjected to hydrophobic modification aiming at a polymerized monomer, ester groups of alkyl ester with strong hydrophobicity are reasonably introduced through the solubilization of a reactive emulsifier, the problems of polymerization uniformity and rationality are solved, the hydrolysis stability of the core polymer is stronger than that of water-soluble ester groups, and good continuous dispersing capability can be provided.
The stable polycarboxylic acid superplasticizer is a polymer with a core-shell structure, and the core structure of the core-shell structure is obtained by emulsion polymerization of a vinyl glycol ether monomer containing a hydrophobic chain segment and a derivative monomer A thereof, an unsaturated carboxylic acid or anhydride monomer B, an alkyl acrylate monomer C and an allyl polyether reactive emulsifier D; the shell structure is obtained by aqueous solution polymerization of a vinyl polyethylene glycol ether monomer and a derivative monomer E thereof, an unsaturated carboxylic acid or anhydride monomer B and a (methyl) acrylic hydroxyl ester unsaturated micromolecule substance F.
The monomer A in the core structure of the invention: a monomer B: the molar ratio of the monomer C is 1 (1-6) to 2-10.
The using amount of the monomer D is 5-20% of the total mass of the monomer B and the monomer C.
In the shell structure: the monomer E: a monomer B: the molar ratio of the monomer F is 1 (3-6) to 2-4.
The structure of the monomer A is in accordance with the general formula (1), and the monomer A is any one monomer or any two or more monomers in accordance with the general formula (1) and is mixed and used in any proportion:
in the general formula (1), R1Represents H or CH3；R2Representative O, OCH2O、OCH2CH2O、OCH2CH2CH2O or OCH2CH2CH2CH2O；R3Represents a H atom; m is the average addition mole number of the propylene oxide and is an integer of 6-40; n is the average addition mole number of the ethylene oxide and is an integer of 20-120; the ratio n/m of the ethylene oxide to the propylene oxide is more than or equal to 3.
R in the general formula (1)1When the monomer A is H, the monomer A is selected from one or more of vinyl polypropylene/glycol ether, hydroxyethyl vinyl polypropylene/glycol ether, hydroxypropyl vinyl polypropylene/glycol ether and hydroxybutyl vinyl polypropylene/glycol ether, and is mixed in any proportion.
R in the general formula (1)1Is CH3When the monomer A is selected from any one or more than one of 3-methyl vinyl polypropylene/glycol ether, 3-methyl-hydroxyethyl vinyl polypropylene/glycol ether, 3-methyl-hydroxypropyl vinyl polypropylene/glycol ether and 3-methyl-hydroxybutyl vinyl polypropylene/glycol ether, the monomer A is mixed at any ratio.
The structure of the monomer B conforms to the general formula (2):
in the general formula (2), R4Represents H or CH3；R5Represents H or COOH; r6Represents H, COOH or CH2COOH, and R5Or R6Must contain a carboxyl group.
The monomer B in the invention is selected from acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride and itaconic anhydride. In the present invention, one or more of the above monomers may be selected and used in combination at an arbitrary ratio.
The structure of the monomer C is represented by the general formula (3):
in the general formula (3), R7Represents H or CH3；R8Represents an alkyl group of 1 to 4 carbon atoms, which is an alkyl (meth) acrylate compound.
The monomer C in the invention is selected from methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate and butyl (meth) acrylate. In actual use, one or more of the components can be selected and mixed at any ratio.
The structure of the monomer D is represented by a general formula (4), and the monomer D is an allyl polyether reactive emulsifier.
In the general formula (4), p is the average addition mole number of propylene oxide and is an integer of 5-40; q is the average addition mole number of the ethylene oxide and is an integer of 2-20; the ratio p/q of the propylene oxide to the ethylene oxide is more than or equal to 2. X represents H, SO3Na and
the monomer D is selected from allyl polypropylene/glycol ether series reactive emulsifiers, and is specifically selected from allyl polypropylene/glycol ether, allyl polypropylene/glycol ether sodium sulfate and allyl polypropylene/glycol ether phosphate.
The structure of the monomer E also corresponds to the general formula (1) except that "m" is 0, wherein:
R1represents H or CH3；R2Representative O, OCH2O、OCH2CH2O、OCH2CH2CH2O or OCH2CH2CH2CH2O；R3Represents a H atom; n is the average addition mole number of the ethylene oxide and is an integer of 20-120;
the monomer E is one or a mixture of more than two of the monomers with the structures in any proportion.
When R in the general formula (1)1When the monomer E is H, the monomer E is selected from any one or more than one of vinyl polyglycol ether, hydroxyethyl vinyl polyglycol ether, hydroxypropyl vinyl polyglycol ether and hydroxybutyl vinyl polyglycol ether, and the monomer E is mixed in any proportion.
When R in the general formula (1)1Is CH3When the monomer E is selected from any one or more than one of 3-methyl vinyl polyglycol ether, 3-methyl-hydroxyethyl vinyl polyglycol ether, 3-methyl-hydroxypropyl vinyl polyglycol ether and 3-methyl-hydroxybutyl vinyl polyglycol ether, the mixture is mixed in any proportion.
The structure of the monomer F corresponds to the general formula (5):
in the general formula (5), R9Represents H or CH3(ii) a x and y are respectively the addition mole number of ethylene oxide and propylene oxide, wherein x is 0 or 1, y is 0 or 1, and x and y are not 0 or 1 at the same time.
In the general formula (5), when R is9When the monomer is H, the unsaturated small molecular monomer F represented by the monomer is hydroxyethyl acrylate,Hydroxypropyl acrylate, hydroxybutyl acrylate; when R is9Is CH3When the unsaturated small molecular monomer F is used, the unsaturated small molecular monomer F is hydroxyethyl methacrylate, hydroxypropyl methacrylate or hydroxybutyl methacrylate.
The weight average molecular weight of the steady-state polycarboxylic acid superplasticizer is 20000-100000. If the molecular weight is too small and too large, it brings about adverse effects on the dispersion property of concrete, slump-retaining property, material suitability, and workability improvement of concrete.
The preparation method of the steady-state polycarboxylic acid superplasticizer adopts a two-step method to synthesize:
(1) preparation of a core structure prepolymer: pre-emulsifying other unsaturated monomers A, B and C by using an unsaturated monomer D with emulsifying activity; the emulsified monomer is polymerized in the presence of an initiator and a chain transfer agent;
(2) preparation of the shell-structured polymer: and polymerizing the monomer E, the monomer B and the monomer F in the core structure prepolymer under the action of an initiator and a chain transfer agent to obtain the polymer.
According to the invention, the initiator can be selected from redox initiators during the polymerization step according to the most suitable initiation rate of the free radical polymerization. Wherein, the oxidant can be one or more than two of hydrogen peroxide aqueous solution, ammonium persulfate, sodium persulfate and potassium persulfate. The reducing agent can be one or more of L-ascorbic acid, sodium formaldehyde sulfoxylate, sodium bisulfite and ferrous sulfate.
The molar usage of the oxidant accounts for 0.5-5% of the total molar number of all the monomers, and the oxidant is added into a reaction system at one time before the polymerization reaction starts.
The molar amount of the reducing agent accounts for 0.1-2.5% of the total molar number of all the monomers.
The chain transfer agent can be a mercapto chain transfer agent, and is specifically selected from one or a mixture of more than two of mercaptoethanol, mercaptopropanol, mercaptoacetic acid and mercaptopropionic acid. The molar usage of the chain transfer agent accounts for 0.5-5% of the total molar number of all the monomers.
The preparation method of the steady-state polycarboxylic acid superplasticizer comprises the following specific steps:
(1) preparation of a core structure prepolymer: the monomer A and water were stirred in a reaction vessel equipped with a stirrer for 1 hour to form a polyether pre-emulsion 1. And (3) placing the monomer B, the monomer C, the monomer D and water in a stirring batching kettle to stir for 1 hour to form a monomer pre-emulsion 2. And (3) heating the reaction system to 10-60 ℃, adding an oxidant into the polyether pre-emulsion 1, beginning to dropwise add the monomer pre-emulsion 2, and dropwise add an aqueous solution containing a reducing agent and a chain transfer agent simultaneously, wherein the nuclear structure prepolymer is formed after all the materials are dropwise added.
(2) Preparation of the shell-structured polymer: and adding the monomer E into a nuclear structure prepolymer reaction system at one time. And when the temperature of the system is stabilized to 10-60 ℃, dropwise adding the aqueous solution of the monomer B and the aqueous solution of the monomer F, dropwise adding the aqueous solution containing a reducing agent and a chain transfer agent simultaneously, and after finishing dropwise adding, carrying out heat preservation reaction for 1 hour and then neutralizing to obtain the stable polycarboxylic acid superplasticizer.
The polymerization reaction temperature is 10-60 ℃, the monomer conversion speed and efficiency of a polymerization system can be reduced when the temperature is too low, the polymerization system is reacted too fast when the temperature is too high, and the heat release is too large, so that the process control is not facilitated.
The preparation method of the nuclear structure prepolymer is characterized in that the monomer pre-emulsion 2 is added into a reaction system in a continuous dropwise adding mode, and the dropwise adding time is controlled to be 2-5 hours. Too short dripping time can cause too fast reaction, and is not favorable for forming a relatively uniform sequence structure; the dropping time is too long, which causes a decrease in production efficiency.
In the preparation method of the shell structure prepolymer, the aqueous solution of the monomer B and the aqueous solution of the monomer F are added into a reaction system in a continuous dropwise adding mode, and the dropwise adding time is controlled to be 2-5 hours. Too short dripping time can cause too fast reaction, and is not favorable for forming a relatively uniform sequence structure; the dropping time is too long, which causes a decrease in production efficiency.
The aqueous solution containing the reducing agent and the chain transfer agent is added into a reaction system in a continuous dropwise manner, wherein the dropwise adding time of the first reaction step is controlled to be consistent with that of the monomer pre-emulsion 2, and the dropwise adding time of the second reaction step is 0.5 hour longer than that of the aqueous monomer solution.
The neutralization step of the present invention uses a 30% strength caustic soda solution.
The invention controls the mass concentration of the polymerization reaction to be 30-60%, and the polymerization concentration is too low or too high to be beneficial to the polymerization reaction.
The stable polycarboxylic acid superplasticizer can be used as a concrete dispersant, and the conventional mixing amount of the stable polycarboxylic acid superplasticizer is 0.05-0.4% of the total mass of a cement concrete rubber material. If the amount added is less than 0.05%, the dispersing property and reinforcing effect thereof are unsatisfactory. If, on the other hand, the addition is above 0.4%, the overdosing proves to be merely an economic waste, since no corresponding increase in effect is brought about.
The stable polycarboxylate superplasticizer of the present invention can also be mixed with at least one water reducing agent selected from the group consisting of sulfamic acid water reducing agents, lignin water reducing agents, and conventional polycarboxylate water reducing agents known in the art. In addition, besides the above-mentioned known water reducing agent for concrete, air entraining agent, expanding agent, retarder, early strength agent, thickener, shrinkage reducing agent, defoaming agent, etc. may be added thereto according to the actual need.
Compared with the conventional polycarboxylate superplasticizer technology, the stable polycarboxylate superplasticizer provided by the invention has the following obvious difference advantages in polymerization technology, initial dispersion, long-time fluidity maintenance, concrete workability improvement and material adaptability:
(1) the stable polycarboxylic acid superplasticizer is designed into a polymer with a core-shell structure, and the polymerization between monomers occurs between the shell and the core to generate a transitional polymer. The polymerization products in different periods can provide continuous dispersing capacity in different hydration stages of concrete, effectively improves the slump retaining capacity of the water-reducing polycarboxylic acid product, and simultaneously improves the initial dispersing capacity of the slump-retaining polycarboxylic acid product. The problems of high mixing amount, improper slump retaining capacity connection and the like caused by compounding can be effectively solved.
(2) The stable polycarboxylic acid superplasticizer increases the amphiphilic capacity of a polymer, reasonably introduces a comonomer with weak water solubility into a polycarboxylic acid molecular structure through the emulsifying capacity of a reactive emulsifier, solves the problem of uniformity of copolymerization reaction of various monomers, and avoids the problems of incomplete polymerization and nonuniform distribution of monomer sequences in molecules caused by poor water solubility of the monomers.
(3) The stable polycarboxylic acid superplasticizer has the advantages that the comonomer which has alkali response capability in the cement alkaline environment and has longer hydrolysis time requirement is introduced into the molecular structure of the stable polycarboxylic acid superplasticizer and is used as a slow release unit to form the stable polycarboxylic acid superplasticizer, so that the slow release action time is obviously prolonged, and the action timeliness of the polycarboxylic acid superplasticizer is prolonged.
(4) The stable polycarboxylate superplasticizer has stronger hydrophobic capability than the main chain of the conventional polycarboxylate superplasticizer, forms a relatively hydrophobic covering layer after being adsorbed and anchored on the surface of cement particles, is more favorable for discharging free water, improves the water reducing performance of a polymer, and increases the flowing capability of concrete.
(5) The stable polycarboxylic acid superplasticizer has stronger air entraining capacity, can increase the air content of concrete to a certain extent by stirring after being added into a concrete system, is beneficial to improving the workability and material adaptability of the concrete, and does not influence the development of the strength of the concrete.
Detailed Description
The following examples describe in more detail the preparation of the polymer product according to the process of the invention and are given by way of illustration and are intended to enable one skilled in the art to understand the contents of the invention and to carry out the invention, without limiting the scope of the invention in any way. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
The monomers used in the following examples are shown in Table 1 and the synthesized stable polycarboxylic acid superplasticizer is abbreviated as LAPC.
In the examples of the present invention, the weight average molecular weight of the polymer was measured by Agilent 1260 chromatography. (gel column: Shodex SB806+803 two chromatographic columns in series; eluent: 0.1M NaNO3A solution; velocity of mobile phase: 1.0 ml/min; and (3) injection: 20 μ l of 0.5% aqueous solution; a detector: a differential refractive detector; standard substance: polyethylene glycol GPC standards (Sigma-Aldrich, molecular weight 1010000, 478000, 263000, 118000, 44700, 18600, 6690, 1960, 628, 232).
In the application embodiment of the invention, the adopted cement is 52.5 R.P.II cement in a small open field unless otherwise specified, the sand is medium sand with fineness modulus Mx of 2.6, and the stones are continuous graded broken stones with the grain size of 5-20 mm.
The compound numbers described in table 1 were used in the synthesis examples of the present invention:
table 1 example compound designations
Example 1
1300g A-1(1mol) and 400g of water were charged into a reactor equipped with a thermometer and a stirrer, and dissolved at 60 ℃ with stirring and stirred for 1 hour to prepare a pre-emulsion 1. A pre-emulsion 2 was prepared by adding 72g of B-1(1mol), 172.2g of C-1(2mol), 12.2g of D-1(0.027mol) and 300g of water to a compounding vessel and stirring for 1 hour. After 4.56g of 30% hydrogen peroxide solution was added to the pre-emulsion 1, the pre-emulsion 2 was continuously added to the reactor by means of a peristaltic pump for 2 hours. At the same time, 200g of an aqueous solution in which 0.71g L-ascorbic acid and 6.29g of mercaptoethanol were dissolved was continuously fed into the reactor by means of a peristaltic pump over 2 hours.
950g E-1(1mol) was added in one portion to the reactor, and a solution of 216g B-1(3mol), 348g F-1(3mol) and 500g water was added dropwise over 2 hours, starting when the temperature had stabilized to 60 ℃. Simultaneously, 250g of an aqueous solution in which 1.24g of 1.24g L-ascorbic acid and 11g of mercaptoethanol were dissolved was continuously fed into the reactor by means of a peristaltic pump for 2.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 520g of 30% liquid alkali is added for neutralization and discharging, and the stable polycarboxylic acid superplasticizer LAPC-1 with the concentration of 60% is obtained, and the molecular weight is 75000.
Example 2
3200g A-2(1mol) and 2000g of water were charged into a reactor equipped with a thermometer and a stirrer, and dissolved and stirred for 1 hour while controlling the temperature to 10 ℃ under stirring to prepare a pre-emulsion 1. 215g of B-2(2.5mol), 550.5g of C-2(5.5mol), 61.2g of D-3(0.024mol) and 800g of water were added to a compounding tank, and the mixture was stirred for 1 hour to prepare a pre-emulsion 2. After 35g of ammonium persulfate was added to the pre-emulsion 1, the pre-emulsion 2 was continuously added to the reactor by means of a peristaltic pump for 3 hours. Simultaneously, 900g of an aqueous solution in which 2.66g of sodium formaldehyde sulfoxylate and 41.5g of mercaptopropanol were dissolved was continuously fed into the reactor by a peristaltic pump for 3 hours.
2500g E-2(1mol) was added in one portion to the reactor and a solution of 258g of B-2(3mol), 260g of 260g F-2(2mol) and 2000g of water was added dropwise over a period of 3 hours, starting when the temperature had stabilized to 10 ℃. At the same time, 600g of an aqueous solution in which 1.77g of sodium formaldehyde sulfoxylate and 27.7g of mercaptopropanol were dissolved was continuously fed into the reactor by a peristaltic pump for 3.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 730g of 30 percent liquid caustic soda is added for neutralization and discharging, and the steady-state polycarboxylic acid superplasticizer LAPC-2 with the concentration of 50 percent and the molecular weight of 21000 is obtained.
Example 3
5500g A-3(1mol) and 6000g of water were charged into a reactor equipped with a thermometer and a stirrer, and stirred while being heated to 45 ℃ to dissolve and stir for 1 hour to prepare a pre-emulsion 1. 464g of B-3(4mol), 912.8g of C-3(8mol), 165.2g of D-5(0.0038mol) and 2400g of water were added to a compounding kettle, and stirred for 1 hour to prepare a pre-emulsion 2. After 102.4g of sodium persulfate was added to the pre-emulsion 1, the pre-emulsion 2 was continuously fed into the reactor using a peristaltic pump for 4 hours. While 2000g of an aqueous solution in which 10.8g of sodium hydrogensulfite and 35.9g of mercaptopropanol were dissolved was continuously fed into the reactor by a peristaltic pump for 4 hours.
4050g E-3(1mol) was added in one portion to the reactor and a solution of 464g of B-3(4mol), 504g F-3(3.5mol) and 5200g of water was added dropwise over a period of 4 hours, starting when the temperature had stabilized at 45 ℃. While 2000g of an aqueous solution in which 7.1g of sodium hydrogensulfite and 23.5g of mercaptopropanol were dissolved was continuously fed into the reactor by a peristaltic pump for 4.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 600g of 30 percent liquid caustic soda is added for neutralization and discharging, and the steady-state polycarboxylic acid superplasticizer LAPC-3 with the concentration of 40 percent and the molecular weight of 56800 is obtained.
Example 4
7700g A-4(1mol) and 12000g of water were charged into a reactor equipped with a thermometer and a stirrer, and dissolved by heating to 30 ℃ with stirring and stirred for 1 hour to prepare a pre-emulsion 1. 588g of B-4(6mol), 1282g of C-4(10mol), 374g of D-2(0.154mol) and 7000g of water are added into a batching kettle, and stirred for 1 hour to prepare a pre-emulsion 2. After 368.2g of potassium persulfate were added to the pre-emulsion 1, the pre-emulsion 2 was continuously fed into the reactor by means of a peristaltic pump over a period of 5 hours. Meanwhile, 4500g of an aqueous solution in which 119.2g of ferrous sulfate and 9.1g of mercaptopropionic acid were dissolved was continuously fed to the reactor by a peristaltic pump for 5 hours.
5380g E-4(1mol) was added in one portion to the reactor and a solution containing 490gB-4(5mol), 520g F-4(4mol) and 10000g of water was added dropwise over 5 hours, starting when the temperature stabilized to 30 ℃. Meanwhile, 4500g of an aqueous solution in which 70g of ferrous sulfate and 5.4g of mercaptopropionic acid were dissolved was continuously fed to the reactor by a peristaltic pump for 5.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 920g of 30% liquid caustic soda is added for neutralization and discharging, and the stable polycarboxylic acid superplasticizer LAPC-4 with the concentration of 30% is obtained, and the molecular weight is 98500.
Example 5
Into a reactor equipped with a thermometer and a stirrer, 1650g A-5(1mol) and 600g of water were charged, and dissolved by heating to 10 ℃ with stirring and stirred for 1 hour to prepare a pre-emulsion 1. 195g B-5(1.5mol), 300.3g C-5(3mol), 29.7g D-4(0.032mol) and 300g water were added to a compounding kettle and stirred for 1 hour to prepare a pre-emulsion 2. 42.7g of 30% hydrogen peroxide solution was added to the pre-emulsion 1, and the pre-emulsion 2 was continuously added to the reactor by means of a peristaltic pump for 2 hours. At the same time, 300g of an aqueous solution containing 15.4g of ferrous sulfate and 12.7g of thioglycolic acid dissolved therein was continuously fed into the reactor by a peristaltic pump for 2 hours.
1200g E-5(1mol) was added in one portion to the reactor and a solution containing 455g of B-5(3.5mol), 360g F-5(2.5mol) and 550g of water was added dropwise over a period of 2 hours, starting when the temperature had stabilized to 10 ℃. At the same time, 200g of an aqueous solution containing 19.6g of ferrous sulfate and 16.2g of thioglycolic acid dissolved therein was continuously fed into the reactor by a peristaltic pump for 2.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 850g of 30 percent liquid caustic soda is added for neutralization and discharging, and the steady-state polycarboxylic acid superplasticizer LAPC-5 with the concentration of 60 percent and the molecular weight of 42300 is obtained.
Example 6
3050g A-6(1mol) and 3000g of water were charged in a reactor equipped with a thermometer and a stirrer, and dissolved by heating to 25 ℃ with stirring and stirred for 1 hour to prepare a pre-emulsion 1. 224.4g B-6(2mol), 456.4g C-6(4mol), 40.8g D-4(0.033mol) and 1000g water were added to a compounding kettle, and stirred for 1 hour to prepare a pre-emulsion 2. After 128.4g of ammonium persulfate was added to the pre-emulsion 1, the pre-emulsion 2 was continuously fed into the reactor by means of a peristaltic pump for 3 hours. At the same time, 600g of an aqueous solution in which 14.6g of sodium hydrogensulfite and 25.9g of mercaptopropanol were dissolved was continuously fed into the reactor by a peristaltic pump for 3 hours.
2180g E-6(1mol) was added in one portion to the reactor and a solution of 448g of B-6(4mol), 316g F-6(2mol) and 3000g of water was added dropwise over a period of 3 hours, starting when the temperature had stabilized to 25 ℃. While 300g of an aqueous solution in which 14.6g of sodium hydrogensulfite and 25.9g of mercaptopropanol were dissolved was continuously fed into the reactor by a peristaltic pump for 3.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 450g of 30 percent liquid caustic soda is added for neutralization and discharging, and the steady-state polycarboxylic acid superplasticizer LAPC-6 with the concentration of 45 percent and the molecular weight of 37300 is obtained.
Example 7
In a reactor equipped with a thermometer and a stirrer, 3400g A-7(1mol) and 3000g of water were added, and dissolved by heating to 40 ℃ with stirring and stirred for 1 hour to prepare a pre-emulsion 1. 216g B-1(3mol), 768.6g C-7(6mol), 177.2g D-1(0.39mol) and 800g water were added to a compounding kettle and stirred for 1 hour to prepare a pre-emulsion 2. After 169g of sodium persulfate was added to the pre-emulsion 1, the pre-emulsion 2 was continuously fed into the reactor using a peristaltic pump for 4 hours. At the same time, 500g of an aqueous solution in which 18.4g of sodium formaldehyde sulfoxylate and 8.1g of mercaptoethanol were dissolved was continuously fed into the reactor by means of a peristaltic pump for 4 hours.
2820g E-7(1mol) was added in one portion to the reactor and a solution containing 396g of B-1(5.5mol), 348g F-1(3mol) and 2000g of water was added dropwise over 4 hours, starting when the temperature had stabilized at 40 ℃. Simultaneously, 800g of an aqueous solution in which 17.5g of sodium formaldehyde sulfoxylate and 7.7g of mercaptoethanol were dissolved was continuously fed into the reactor by means of a peristaltic pump for 4.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 1150g of 30 percent liquid caustic soda is added for neutralization and discharging, and the steady-state polycarboxylic acid superplasticizer LAPC-7 with the concentration of 50 percent and the molecular weight of 83400 is obtained.
Example 8
In a reactor equipped with a thermometer and a stirrer, 6250g A-8(1mol) and 4000g of water were charged, and dissolved by heating to 50 ℃ with stirring and stirred for 1 hour to prepare a pre-emulsion 1. 715.6g B-5(5.5mol), 1137.6g C-8(8mol), 185.3g D-4(0.2mol) and 1800g water are added into a batching kettle and stirred for 1 hour to prepare the pre-emulsion 2. After 302g of potassium persulfate was added to the pre-emulsion 1, the pre-emulsion 2 was continuously fed into the reactor using a peristaltic pump for 5 hours. At the same time, 600g of an aqueous solution in which 46.6g L-ascorbic acid and 46.7g of mercaptopropionic acid were dissolved was continuously fed into the reactor by means of a peristaltic pump for 5 hours.
4500g E-8(1mol) was added in one portion to the reactor, and a solution containing 780g B-5(6mol), 432g F-5(3mol) and 3200g of water was added dropwise over a period of 5 hours, starting when the temperature had stabilized at 50 ℃. Simultaneously, 1000g of an aqueous solution in which 32.1g L-ascorbic acid and 32.2g of mercaptopropionic acid were dissolved was continuously fed into the reactor by means of a peristaltic pump for 5.5 hours. After all the materials are added, the reaction is carried out for 1 hour under the condition of heat preservation, 950g of 30 percent liquid caustic soda is added for neutralization and discharging, and the stable polycarboxylic acid superplasticizer LAPC-8 with the concentration of 55 percent and the molecular weight of 48900 is obtained.
Comparative example 1
Adding 1800g of deionized water and 3000g of vinyl polyglycol ether (1mol) into a glass reactor provided with a thermometer and a stirrer, heating to 45 ℃ while stirring for dissolution, then adding 20.4g of 30% hydrogen peroxide, and stirring uniformly. Then 360g of acrylic acid (5mol) and 400g of water are mixed and stirred to prepare a uniform monomer aqueous solution, the monomer aqueous solution is dripped into a reactor for 2 hours, 500g of an aqueous solution containing 10.5g L-ascorbic acid and 19g of mercaptopropionic acid is dripped simultaneously for about 2.5 hours, the temperature is kept for reaction for 1 hour after the dripping is finished, 650g of 30 percent liquid alkali is added for neutralization and discharging, and the polycarboxylic acid water reducing agent PC-1 with the concentration of 50 percent is obtained and the molecular weight is 45000.
Comparative example 2
2000g of deionized water and 2000g of hydroxypropyl vinyl polyethylene glycol ether (1mol) are added into a glass reactor provided with a thermometer and a stirrer, the temperature is raised to 15 ℃ while stirring, the mixture is dissolved, 17.1g of ammonium persulfate is added, and the mixture is stirred uniformly. Then 196g of maleic anhydride (2mol), 522g of hydroxyethyl acrylate (4.5mol) and 500g of water are mixed and stirred to prepare a uniform monomer aqueous solution, the monomer aqueous solution is dripped into a reactor for 3.5 hours, 200g of an aqueous solution containing 1.56g of sodium bisulfite and 17.5g of mercaptoethanol is dripped simultaneously for about 4 hours, after the dripping is finished, the reaction is kept for 1 hour, 300g of 30 percent liquid caustic soda is added for neutralization and discharging, and the polycarboxylate water reducer PC-2 with the concentration of 40 percent and the molecular weight of 26000 is obtained.
Comparative example 3
10000g of deionized water and 6500g of 3-methyl hydroxy butyl vinyl polyglycol ether (1mol) are added into a glass reactor provided with a thermometer and a stirrer, the temperature is raised to 60 ℃ while stirring for dissolution, and then 162.2g of potassium persulfate is added and stirred uniformly. Then, 520.4g of itaconic acid (4mol), 910g of hydroxypropyl acrylate (7mol) and 8000g of water are mixed, stirred to prepare a uniform monomer aqueous solution, the monomer aqueous solution is dripped into a reactor for 5 hours, 1000g of an aqueous solution containing 35.4g of sodium formaldehyde sulfoxylate and 11g of mercaptopropanol is dripped simultaneously for about 5.5 hours, after the dripping is finished, the reaction is kept for 1 hour, 600g of 30% liquid caustic soda is added for neutralization and discharging, and the 30% polycarboxylic acid water reducing agent PC-2 with the molecular weight of 73000 is obtained.
Application example 1:
testing the fluidity of the cement paste: according to the GB/T8077-2012 standard, 300g of 52.5R.P. II cement is adopted in a small open field, the water adding amount is 87g, and the net cement slurry fluidity is measured on flat glass after the stirring is finished. The results of the cement paste fluidity test are shown in Table 2.
TABLE 2 neat paste fluidity test
As can be seen from the test results in Table 2, compared with the PC-1 water-reducing water reducer prepared in comparative example 1, the steady-state polycarboxylate superplasticizer prepared by the method of the invention has slightly weaker water-reducing polycarboxylic acid in the aspect of water-reducing capability, and the fluidity maintaining capability of the series of steady-state polycarboxylate superplasticizer samples has very obvious advantages. Compared with the slump-retaining polycarboxylate superplasticizers PC-2 and PC-3 prepared in the comparative examples 2 and 3, the initial water reducing capacity of the series of stable polycarboxylate superplasticizers is far stronger than that of the comparative examples, the fluidity maintaining capacity in the middle and later periods is remarkably improved, the fluidity maintaining capacity in the later periods is particularly shown to be a continuously increased trend, and the fluidity maintaining time of cement paste is remarkably prolonged.
Application example 2:
testing air content, compressive strength and slump: the air content is determined according to the relevant specified test method of GB8076-2008 concrete admixture; the concrete compressive strength is tested according to relevant regulations of GB/T50081-2016 standard of test method for mechanical properties of common concrete; slump tests and slump loss tests over time are carried out according to relevant regulations of GB50080-2016 standard on common concrete mixture performance test methods. In the test, the water-cement ratio of the concrete is fixed, and the mixing amount of the water reducing agent is adjusted to ensure that the initial slump of the fresh concrete is 21 +/-1 cm, and the test result is shown in Table 3.
TABLE 3 concrete Properties
Note: the concrete of the configurations 10 and 11 incorporated PC-1 as a water-reducing component in an amount of 0.1% of the cementitious material.
The tests show that the series of stable polycarboxylic acid superplasticizers prepared by the method can obtain equivalent initial dispersing performance at a mixing amount lower than that of the conventional polycarboxylic acid slump retaining agent, and show very obvious advantages in slump retaining performance. The concrete prepared by the sample of the invention still has good fluidity within 5h, and shows very stable slump retaining effect, while the concrete prepared by the sample of the comparative example has obvious concrete fluidity loss within 1-3 h. The excellent steady-state slump retaining capacity particularly meets the pouring construction of concrete with long-distance transportation requirements and concrete with an ultra-large volume, can effectively ensure the construction quality of the concrete, and brings obvious economic benefits and social benefits.
The sample has certain air-entraining performance, and the air-entraining capacity of the sample is superior to that of the conventional polycarboxylic acid water reducing agent. It is particularly important that the steady-state polycarboxylic acid superplasticizer prepared by the invention does not influence the setting time of concrete and the normal development of concrete strength.
The invention can be realized by all the listed raw materials and the upper and lower limit values of the raw materials, and the examples are not listed.
Claims (17)
1. The stable polycarboxylic acid superplasticizer is characterized in that the stable polycarboxylic acid superplasticizer is a polymer with a core-shell structure, and the core structure of the core-shell structure is obtained by emulsion polymerization of a vinyl glycol ether monomer containing a hydrophobic chain segment and a derivative monomer A thereof, an unsaturated carboxylic acid or anhydride monomer B, an alkyl acrylate monomer C and an allyl polyether reactive emulsifier D; the shell structure is obtained by aqueous solution polymerization of a vinyl polyethylene glycol ether monomer and a derivative monomer E thereof, an unsaturated carboxylic acid or anhydride monomer B and a (methyl) acrylic hydroxyl ester unsaturated micromolecule substance F;
monomer a of the core structure: a monomer B: the molar ratio of the monomer C is 1 (1-6) to 2-10;
the using amount of the monomer D is 5-20% of the total mass of the monomer B and the monomer C;
monomer E of the shell structure: a monomer B: the molar ratio of the monomer F is 1 (3-6) to 2-4.
2. The stable polycarboxylate superplasticizer according to claim 1, wherein said monomer A has a structure corresponding to general formula (1), and is any one monomer or a mixture of any two or more monomers in any ratio corresponding to general formula (1):
in the general formula (1), R1Represents H or CH3；R2Representative O, OCH2O、OCH2CH2O、OCH2CH2CH2O or OCH2CH2CH2CH2O；R3Represents a H atom; m is the average addition mole number of the propylene oxide and is an integer of 6-40; n is the average addition mole number of the ethylene oxide and is an integer of 20-120; the ratio n/m of the ethylene oxide to the propylene oxide is more than or equal to 3.
3. A stable polycarboxylic acid superplasticizer according to claim 2, wherein monomer A is selected from any one or more of vinyl polypropylene/glycol ether, hydroxyethyl vinyl polypropylene/glycol ether, hydroxypropyl vinyl polypropylene/glycol ether, hydroxybutyl vinyl polypropylene/glycol ether, 3-methyl-hydroxyethyl vinyl polypropylene/glycol ether, 3-methyl-hydroxypropyl vinyl polypropylene/glycol ether, 3-methyl-hydroxybutyl vinyl polypropylene/glycol ether in any ratio.
4. The stationary polycarboxylic acid superplasticizer of claim 1, wherein said monomer B has a structure conforming to general formula (2):
in the general formula (2), R4Represents H or CH3；R5Represents H or COOH; r6Represents H, COOH or CH2COOH, and R5Or R6Must contain a carboxyl group.
5. The stable polycarboxylic acid superplasticizer of claim 4, wherein said monomer B is selected from any one or more of acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride and itaconic anhydride, and is mixed in any ratio.
6. The stationary polycarboxylic acid superplasticizer of claim 1, wherein said monomer C has a structure represented by general formula (3):
in the general formula (3), R7Represents H or CH3；R8Represents an alkyl group of 1 to 4 carbon atoms, which is an alkyl (meth) acrylate compound.
7. The stationary polycarboxylic acid superplasticizer of claim 6, wherein said monomer C is selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and mixtures thereof in any ratio.
8. The stationary polycarboxylic acid superplasticizer of claim 1, wherein said allyl polyether reactive emulsifier monomer D has a structure represented by general formula (4):
in the general formula (4), p is the average addition mole number of propylene oxide and is an integer of 5-40; q is the average addition mole number of the ethylene oxide and is an integer of 2-20; the ratio p/q of the propylene oxide to the ethylene oxide is more than or equal to 2; x represents H, SO3Na and
9. a stable polycarboxylic acid superplasticizer according to claim 8, wherein said monomer D is a reactive emulsifier of the allyl polypropylene/glycol ether series selected from the group consisting of allyl polypropylene/glycol ether, sodium allyl polypropylene/glycol ether sulphate or allyl polypropylene/glycol ether phosphate.
10. The stationary polycarboxylic superplasticizer of claim 1, wherein said monomer E also has the structure according to formula (1) except that "m" is 0, as detailed below:
R1represents H or CH3；R2Representative O, OCH2O、OCH2CH2O、OCH2CH2CH2O or OCH2CH2CH2CH2O；R3Represents a H atom; n is the average addition mole number of the ethylene oxide and is an integer of 20-120;
the monomer E is any one or a mixture of two or more of the monomers with the structures in any proportion.
11. A stable polycarboxylic acid superplasticizer according to claim 10, wherein said monomer E is selected from any one or more of vinyl polyethylene glycol ether, hydroxyethyl vinyl polyethylene glycol ether, hydroxypropyl vinyl polyethylene glycol ether, hydroxybutyl vinyl polyethylene glycol ether, 3-methyl-hydroxyethyl vinyl polyethylene glycol ether, 3-methyl-hydroxypropyl vinyl polyethylene glycol ether, 3-methyl-hydroxybutyl vinyl polyethylene glycol ether in any proportion.
12. The stationary polycarboxylic superplasticizer of claim 1, wherein said monomer F has a structure conforming to general formula (5):
in the general formula (5), R9Represents H or CH3(ii) a x and y are respectively the addition mole number of ethylene oxide and propylene oxide, wherein x is 0 or 1, y is 0 or 1, and x and y are not 0 or 1 at the same time.
13. The stable polycarboxylic acid superplasticizer of claim 12, wherein said monomer F is one or a mixture of two or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and hydroxybutyl methacrylate.
14. The stable polycarboxylic acid superplasticizer of claim 1, wherein said stable polycarboxylic acid superplasticizer has a weight average molecular weight of 20000 to 100000.
15. The method for preparing a stable polycarboxylic acid superplasticizer according to claims 1-14, characterized in that the synthesis is carried out by a two-step process:
(1) preparation of a core structure prepolymer: pre-emulsifying an unsaturated monomer A, a monomer B and a monomer C by using an unsaturated monomer D with emulsifying activity; emulsion polymerization is carried out on the emulsified monomer in the presence of an initiator and a chain transfer agent to obtain the emulsion;
(2) preparation of the shell-structured polymer: carrying out aqueous solution polymerization on a monomer E, a monomer B and a monomer F in the core structure prepolymer under the action of an initiator and a chain transfer agent to obtain the polymer;
the initiator is a redox initiator, and the oxidant is one or a mixture of more than two of aqueous hydrogen peroxide solution, ammonium persulfate, sodium persulfate and potassium persulfate; the reducing agent can be one or more of L-ascorbic acid, sodium formaldehyde sulfoxylate, sodium bisulfite and ferrous sulfate;
the molar amount of the oxidant accounts for 0.5-5% of the total molar number of all the monomers, and the oxidant is added into a reaction system at one time before the polymerization reaction begins;
the molar amount of the reducing agent accounts for 0.1-2.5% of the total molar number of all the monomers;
the chain transfer agent is a mercapto chain transfer agent, and is specifically selected from one or a mixture of more than two of mercaptoethanol, mercaptopropanol, mercaptoacetic acid and mercaptopropionic acid; the molar usage of the chain transfer agent accounts for 0.5-5% of the total molar number of all the monomers.
16. The method according to claim 15, characterized in that the specific steps are summarized as follows:
(1) preparation of a core structure prepolymer: placing the monomer A and water in a reaction kettle with a stirrer, and stirring for 1 hour to form polyether pre-emulsion 1; placing the monomer B, the monomer C, the monomer D and water in a stirring batching kettle to stir for 1 hour to form a monomer pre-emulsion 2; heating the reaction system to 10-60 ℃, adding an oxidant into the polyether pre-emulsion 1, continuously dropwise adding the monomer pre-emulsion 2, dropwise adding an aqueous solution containing a reducing agent and a chain transfer agent simultaneously, controlling the dropwise adding time to be 2-5 hours, and forming a core-structure prepolymer after all the materials are dropwise added;
(2) preparation of the shell-structured polymer: adding a monomer E into a nuclear structure prepolymer reaction system at one time; when the temperature of the system is stabilized to 10-60 ℃, continuously dropwise adding the aqueous solution of the monomer B and the aqueous solution of the monomer F, wherein the dropwise adding time is controlled to be 2-5 hours; and simultaneously dropwise adding an aqueous solution containing a reducing agent and a chain transfer agent, and neutralizing after the dropwise adding and carrying out heat preservation reaction for 1 hour to obtain the stable polycarboxylic acid superplasticizer.
17. Use of a stationary polycarboxylic acid superplasticizer according to claims 1 to 14,
the stable polycarboxylic acid superplasticizer is used as a concrete dispersant, and the conventional mixing amount of the stable polycarboxylic acid superplasticizer is 0.05-0.4% of the total mass of the cement concrete glue material;
the steady-state polycarboxylate superplasticizer can also be mixed with at least one of sulfamic acid water reducing agents, lignin common water reducing agents and existing polycarboxylate water reducing agents known in the prior art for use;
or adding air entraining agent, expanding agent, retarder, early strength agent, thickening agent, shrinkage reducing agent and defoaming agent for mixing.
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| CN113773450A (en) * | 2021-09-30 | 2021-12-10 | 重庆三圣实业股份有限公司 | Low-temperature low-sensitivity strong-adsorption type polycarboxylate superplasticizer and preparation method thereof |
| CN114685727A (en) * | 2020-12-29 | 2022-07-01 | 南京博特新材料有限公司 | Particle type phosphonic acid group superplasticizer, preparation method and application thereof |
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| CN110396157A (en) * | 2019-08-07 | 2019-11-01 | 广州市建筑科学研究院有限公司 | Sustained-release polycarboxylic nanometer water-reducing agent and its preparation method and application |
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| CN110396157A (en) * | 2019-08-07 | 2019-11-01 | 广州市建筑科学研究院有限公司 | Sustained-release polycarboxylic nanometer water-reducing agent and its preparation method and application |
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| CN114685727A (en) * | 2020-12-29 | 2022-07-01 | 南京博特新材料有限公司 | Particle type phosphonic acid group superplasticizer, preparation method and application thereof |
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| CN113603840B (en) * | 2021-09-06 | 2023-09-19 | 抚顺东科精细化工有限公司 | Preparation method of rust-proof slow-release polycarboxylic acid superplasticizer |
| CN113773450A (en) * | 2021-09-30 | 2021-12-10 | 重庆三圣实业股份有限公司 | Low-temperature low-sensitivity strong-adsorption type polycarboxylate superplasticizer and preparation method thereof |
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