CN108003301B - Preparation method of viscosity-reducing polycarboxylate superplasticizer - Google Patents
Preparation method of viscosity-reducing polycarboxylate superplasticizer Download PDFInfo
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- CN108003301B CN108003301B CN201711123413.9A CN201711123413A CN108003301B CN 108003301 B CN108003301 B CN 108003301B CN 201711123413 A CN201711123413 A CN 201711123413A CN 108003301 B CN108003301 B CN 108003301B
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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
- C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
- C08F283/06—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals
- C08F283/065—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals on to unsaturated polyethers, polyoxymethylenes or polyacetals
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/302—Water reducers
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Abstract
The invention provides a preparation method of a viscosity-reducing polycarboxylate superplasticizer, which is prepared by bulk polymerization and specifically comprises the following steps: (1) mixing polyoxyethylene polyoxypropylene ether and polyoxyethylene ether, controlling the temperature to be 40-60 ℃, uniformly stirring, and then adding an initiator and a mixture of unsaturated carboxylic acid, unsaturated carboxylic acid hydroxyalkyl ester and a chain transfer agent; (2) and (2) curing for 1-1.5 h after the step (1) is finished, and cooling to obtain the viscosity-reducing polycarboxylic acid water reducer. The bulk polymerization reaction is carried out at relatively low temperature, and has strong operability, mild condition and low energy consumption. The polycarboxylate superplasticizer prepared by the method is liquid at normal temperature, has the effective concentration of 100 percent, has stable storage performance and is suitable for long-distance transportation and use; meanwhile, the water reducing agent can effectively reduce the viscosity of concrete mixtures, is beneficial to concrete stirring, transportation and pumping, and is suitable for popularization and application of high-rise engineering and high-performance concrete.
Description
Technical Field
The invention belongs to the technical field of concrete admixtures, and particularly relates to a preparation method of a viscosity-reducing polycarboxylic acid water reducer.
Background
Concrete has become the foundation of human life and is the largest building material used at present. The concrete admixture is a fifth component in concrete except cement, sand, stone and water, and plays a very important role in the application of high-performance concrete. As one kind of concrete admixture, the water reducing agent (also called super plasticizer) can reduce the water consumption for mixing and improve the concrete strength under the condition of unchanged concrete workability and cement consumption, and becomes a focus of research and development in the field of concrete admixtures. The water reducing agent obstructs or destroys the flocculation structure of cement particles through surface activity, complexation, electrostatic repulsion force or three-dimensional repulsion force, and the like, thereby saving the cement consumption and ensuring the workability and strength of concrete. The polycarboxylate superplasticizer has the advantages of low mixing amount, high water reducing rate, high degree of freedom of molecular structure design, environmental friendliness and the like, is known as a third-generation concrete superplasticizer, and is widely applied to projects such as highways, bridges, tunnels, high-rise buildings and the like.
In the concrete industry, it is common knowledge to improve the strength and durability of concrete, especially the great demand of high-strength concrete (C60, C60 means that the compressive strength of the concrete is not less than 60MPa in 28 days under the standard curing condition) and ultra-high strength concrete (C100, C100 means that the compressive strength of the concrete is not less than 100MPa in 28 days under the standard curing condition), so that the concrete technology is rapidly developed. The adoption of the low water-cement ratio is one of the key measures for ensuring the concrete strength and improving the concrete durability, but the reduction of the water-cement ratio also causes the concrete viscosity to be higher, 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 admixture 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 like balls, the friction resistance among aggregate particles is reduced, and therefore viscosity is reduced, but the viscosity reducing effect of the air entraining agent is limited, and the introduced bubbles have adverse effects on the strength of high-strength concrete. In the aspect of admixture, the working performance of concrete is mainly improved by doping a large amount of fly ash at present, although the viscosity of concrete can be reduced by doping fly ash, the viscosity reduction effect of high-rise, high-strength or ultrahigh-strength concrete is very limited. Therefore, how to solve the problem of the increase of the concrete viscosity caused by the adoption of low water-cement ratio in the preparation process of preparing high-strength or ultra-high-strength concrete is a problem which needs to be solved urgently in the field of concrete admixtures.
The excellent water reducing performance of the polycarboxylate water reducing agent is widely accepted by the industry, however, a large number of engineering examples and researches show that the polycarboxylate water reducing agent has the problem of poor compatibility with concrete raw materials. The aggregate is used as the main component of the concrete, and the clay in the aggregate has huge specific surface area, so that a large amount of mixing water can be adsorbed, and the fluidity of the cement concrete is reduced; on the other hand, the clay and the cement particles compete to absorb the carboxylic acid water reducing agent, so that the fluidity of cement concrete is influenced, the viscosity of a concrete mixture is obviously increased, and the engineering pumping and high-rise engineering construction are not facilitated.
Disclosure of Invention
Therefore, the invention aims to solve the technical problem that the viscosity of concrete mixture cannot be effectively reduced by the polycarboxylic acid water reducing agent in the prior art.
Therefore, the invention provides a preparation method of a viscosity-reducing polycarboxylic acid water reducer, which is prepared through bulk polymerization and specifically comprises the following steps:
(1) mixing polyoxyethylene polyoxypropylene ether and polyoxyethylene ether, controlling the temperature to be 40-60 ℃, uniformly stirring, and then adding an initiator and a mixture of unsaturated carboxylic acid, unsaturated carboxylic acid hydroxyalkyl ester and a chain transfer agent;
in the step (1), the polyoxyethylene polyoxypropylene ether has a structure shown in a formula I,
wherein R is1Is methyl or ethyl, R2Hydrogen or methyl, EO is oxyethylene, PO is oxypropylene; m is 30-50, n is 0-20;
(2) and (2) curing for 1-1.5 h after the step (1) is finished, and cooling to obtain the viscosity-reducing polycarboxylic acid water reducer.
According to the preparation method, the mixture is dripped in a single tube at a constant speed within 1.5-2 hours.
The preparation method further comprises the following steps: and neutralizing the polycarboxylate superplasticizer with hydroxyethyl ethylenediamine to a pH value of 6-7 after the viscosity-reducing polycarboxylate superplasticizer is prepared.
In the above preparation method, in the step (1), the ratio of polyoxyethylene polyoxypropylene ether: polyoxyethylene ether: initiator: the mass ratio of the chain transfer agent is 1: (0.25-1) and (0.01-0.03): (0.01-0.03).
In the preparation method, the polyoxyethylene polyoxypropylene ether is at least one of isobutylene polyoxyethylene polyoxypropylene ether and isopentenyl polyoxyethylene polyoxypropylene ether, and the molecular weight of the polyoxyethylene polyoxypropylene ether is 1500-2400.
The above preparation method, the polyoxyethylene polyoxypropylene ether is prepared by the following steps:
mixing unsaturated alcohol serving as an initiator with an alkali catalyst, and adding ethylene oxide and propylene oxide in an oxygen-free environment, wherein the mass ratio of the ethylene oxide to the propylene oxide is 1: (0.1 to 0.3); the unsaturated alcohol and the ethylene oxide are subjected to polymerization reaction with the propylene oxide, the reaction temperature is controlled to be 100-130 ℃, and a reaction product containing unsaturated polyoxyethylene polyoxypropylene ether is prepared;
wherein the unsaturated alcohol is at least one of isobutene alcohol and isopentenol.
In the preparation method, the polyoxyethylene ether is isopentenyl polyoxyethylene ether, and the molecular weight of the polyoxyethylene ether is 500-1000.
In the above preparation method, the unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, itaconic acid and maleic acid.
In the above preparation method, the unsaturated hydroxyalkyl carboxylate is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and vinyl acetate.
In the above preparation method, the initiator is at least one of dimethyl azobisisobutyrate, azobisisobutyronitrile and diisopropyl peroxydicarbonate.
In the preparation method, the chain transfer agent is mercaptoethanol.
In the preparation method, the temperature in the step (3) is reduced to be less than or equal to 30 ℃.
Compared with the prior art, the invention has the following advantages:
1. the preparation method of the viscosity-reducing polycarboxylate superplasticizer provided by the invention can synthesize the polycarboxylate superplasticizer which is liquid at normal temperature and has the effective concentration of 100%. The molecular structure and the molecular weight range of the polyether macromonomer provided by the invention have low melting temperature, the reaction temperature of bulk polymerization reaction is reduced, the synthetic reaction can be carried out at 40-60 ℃, the phenomena of local implosion and the like caused by high temperature in the bulk polymerization reaction process are avoided, the reaction rate is controllable, a polycarboxylic acid water reducing agent with the effective concentration of 100% is synthesized in a solvent-free environment, and the synthesized water reducing agent has the performance of a product synthesized in an aqueous solution environment.
On the other hand, the polyoxyethylene polyoxypropylene ether leads polyoxyethylene polyoxypropylene ether side chains with terminal methyl groups and terminal unsaturated alkenyl groups into the synthesized polycarboxylate water reducer, the polyoxyethylene polyoxypropylene ether and the polyoxyethylene ether are matched with each other to synthesize the polycarboxylate water reducer which is liquid at normal temperature and stable in performance, the synthesized polycarboxylate water reducer has polyether side chains with matched length, a good extension conformation is formed, and the water reducer can play a good steric hindrance effect after being adsorbed on cement particles to continuously provide dispersing capacity. The water reducing agent can be barreled and transported after being synthesized in a liquid state at normal temperature, and does not need to be cooled, solidified and crushed, so that the product synthesis process is simplified, and the production cost of the product is reduced; the synthesized polycarboxylate superplasticizer has stable performance, can not be separated out due to the rise of environmental temperature and the increase of storage time, is suitable for long-distance transportation, and greatly reduces the transportation cost.
Due to the molecular structure of the polyoxyethylene polyoxypropylene ether, a hydrophobic group with a methyl terminal is introduced into a polyether long chain, the HLB value of the synthesized polycarboxylic acid water reducing agent is effectively reduced, and the reduction of the HLB value can reduce the capability of associated water of the polyether long chain, so that more free water is released, and the viscosity of concrete is effectively reduced.
In the preparation method provided by the invention, two polyether monomers are matched with each other, and form an alkane main chain with carboxylic acid groups and a hydrophilic polyether side chain comb-shaped molecular structure with unsaturated carboxylic acid and unsaturated carboxylic acid hydroxyalkyl ester under the action of an initiator and a chain transfer agent. Unsaturated carboxylic acid hydroxyalkyl ester small monomers in the synthetic raw materials can partially replace unsaturated carboxylic acid, a carboxylic acid hydroxyalkyl ester group is introduced to the main chain of the polycarboxylate water reducer at the same time, the carboxylic acid hydroxyalkyl ester group can be slowly hydrolyzed in the cement alkaline environment to release a carboxyl group and micromolecular alcohol, the carboxyl group can be adsorbed on cement, so that the water reducer is ensured to be more firmly adsorbed on cement particles and is not easily adsorbed by soil, the dispersity of concrete is improved through slow release, in addition, the released micromolecular alcohol can be intercalated into clay, so that the adsorption of the clay on the water reducer is reduced, and the viscosity of a concrete mixture is effectively reduced. The polycarboxylate superplasticizer prepared by the preparation method has excellent viscosity reduction performance, can effectively improve the fluidity of concrete mixtures, is beneficial to concrete stirring, transportation and pumping, brings good construction conditions for concrete engineering, and is suitable for popularization and application of high-rise engineering and high-performance concrete.
The reaction process of bulk polymerization does not need water or an organic solvent, thereby avoiding the toxic action of the organic solvent, and the reaction process is green and environment-friendly and has high environmental friendliness.
2. According to the preparation method provided by the invention, the mixture of the unsaturated carboxylic acid hydroxyalkyl ester, the unsaturated carboxylic acid and the molecular weight regulator is dripped at a constant speed, and the dripping time is controlled, so that the constant reaction rate is favorably kept, the molecular weight of the synthesized polycarboxylic acid water reducing agent is improved, the distribution range of the polycarboxylic acid water reducing agent is narrowed, the applicability of the product to concrete raw materials is enhanced, and the viscosity reduction effect of the polycarboxylic acid water reducing agent is improved.
3. The mass ratio of the polyoxyethylene polyoxypropylene ether, the polyoxyethylene ether, the initiator and the chain transfer agent ensures high conversion rate of polymerization reaction on one hand, and can adjust the matching proportion of polyether side chains with different lengths on the polycarboxylate superplasticizer on the other hand, avoid difficult mutual winding among the side chains, ensure that the side chains form good stretching conformation, enable the steric hindrance effect of the polycarboxylate superplasticizer side chains and the electrostatic repulsion force of the carboxylic acid groups on the polycarboxylate superplasticizer main chain to act synergistically, hinder and destroy the flocculation structure of cement particles, thereby saving the cement consumption, ensuring the activity and the strength of concrete and improving the application performance of the polycarboxylate superplasticizer.
4. The specific types of the polyoxyethylene polyoxypropylene ether and the polyoxyethylene ether selected by the invention have proper space chemical structures and polymerization reaction activation energy, and the polyoxyethylene polyoxypropylene ether and the polyoxyethylene ether are matched with each other, can be used as effective reaction media to participate in polymerization reaction, reduce the temperature of bulk polymerization reaction, improve the reaction polymerization rate, effectively control the reaction efficiency, and synthesize the polycarboxylic acid water reducing agent which has high water reducing performance, is liquid at normal temperature and has the effective content of 100%. The polyoxyethylene ether with the molecular weight of 500-1000 has a lower melting point than that of the polyoxyethylene ether with the high molecular weight, and the completion of the bulk polymerization reaction in a relatively low-temperature environment is guaranteed.
5. According to the invention, the selected unsaturated carboxylic acid, the selected unsaturated carboxylic ester, the selected initiator and the selected chain transfer agent are effectively matched with the two polyether monomers, so that the high polymerization efficiency of bulk polymerization is ensured, the reaction rate of the unsaturated carboxylic acid at the reaction temperature of 40-60 ℃ is controllable, the self-polymerization phenomenon of the unsaturated carboxylic acid is reduced, and the possibility of overlong main chain of the polycarboxylic acid water reducing agent is avoided.
The initiator selected by the invention has proper activation energy, can be matched with the melting temperature of the polyether composition to initiate bulk polymerization reaction at the temperature of 40-60 ℃, has proper reaction rate, can avoid side reaction caused by excessively fast reaction rate, and ensures that the synthesized polycarboxylic acid water reducing agent has high water reducing performance.
According to the invention, mercaptoethanol is selected as a chain transfer agent, so that the comb-shaped polycarboxylic acid molecule with a compact structure and high sequence regularity is formed, and the synthesized product has a narrow molecular weight distribution range and a proper size. In addition, the mercaptoethanol has the advantages of strong chain transfer activity, low toxicity and strong operability, and the addition amount is small under the requirement of the mixing amount of the same proportion, so that the reaction cost can be reduced. Compared with chain transfer agents such as mercaptopropionic acid, mercaptoacetic acid and the like, mercaptoethanol has stronger chain transfer activity and strong controllability of molecular weight, can greatly adjust the viscosity of a system by changing the addition amount, and is suitable for the viscosity reduction type polycarboxylic acid water reducing agent.
Detailed Description
The embodiments of the present invention are illustrated below by specific examples, and unless otherwise indicated, the experimental methods disclosed in the present invention are performed by using conventional techniques in the art, and reagents and raw materials used in the examples are commercially available.
Example 1
The embodiment provides a synthesis method of a polycarboxylate superplasticizer, which specifically comprises the following steps:
1. preparation of Isopentenyl polyoxyethylene polyoxypropylene Ether
(1) 85g of prenol and 0.15g of KOH were added to the reaction vessel, and the atmosphere in the vessel was replaced with nitrogen.
(2) And (3) after the temperature of the kettle rises to 100-110 ℃, introducing 1650g of ethylene oxide and 350g of propylene oxide, keeping the polymerization reaction temperature at 130 ℃, the reaction pressure at 0.15Mpa, and curing for 3 hours to obtain a reaction product containing the isopentenyl polyoxyethylene polyoxypropylene ether.
(3) The reaction product was neutralized and degassed in the reactor to obtain isopentenyl polyoxyethylene polyoxypropylene ether with m-15, n-20 and average molecular weight of 1892.38.
2. Preparation of polycarboxylic acid water reducing agent
(1) 200g of the prenylpolyoxyethylene polyoxypropylene ether (m 15, n 20, average molecular weight 1892.38) synthesized in step 1 was charged into a four-neck flask, 100g of the prenylpolyoxyethylene ether (average molecular weight 1000) was added thereto, and the mixture was heated to 40 ℃ and dissolved with stirring.
(2) 6g of dimethyl azobisisobutyrate was added to the kettle while controlling the temperature at 60 ℃ and stirred for 10min, and then a mixed solution (mass concentration: 98%) comprising 40g of acrylic acid, 5g of hydroxyethyl acrylate and 2g of mercaptoethanol was added dropwise through a single tube at a constant rate over a period of 2 hours.
(3) After the dropwise addition is finished, continuously curing for 1.5h, and then cooling to 30 ℃ to prepare the liquid viscosity-reducing polycarboxylate superplasticizer.
(4) And (3) adding hydroxyethyl ethylenediamine into the liquid viscosity-reducing polycarboxylate superplasticizer for neutralization, and adjusting the pH to 6 to obtain the viscosity-reducing polycarboxylate superplasticizer with the effective concentration of 100%.
Example 2
The embodiment provides a synthesis method of a polycarboxylate superplasticizer, which specifically comprises the following steps:
1. preparation of isobutylene-based polyoxyethylene polyoxypropylene Ether
(1) 90g of isobutylene alcohol and 0.20g of KOH were charged into the reaction vessel, and the atmosphere in the vessel was replaced with nitrogen.
(2) After the temperature of the kettle rises to 100 ℃, 1250g of ethylene oxide and 450g of propylene oxide are introduced, the polymerization temperature is kept at 130 ℃, the reaction pressure is 0.20Mpa, and after curing for 3 hours, the reaction product containing the isobutylene polyoxyethylene polyoxypropylene ether is prepared.
(3) The reaction product was neutralized and degassed in the reactor to obtain an isobutylene polyoxyethylene polyoxypropylene ether having an average molecular weight of 1551.8, wherein m is 30 and n is 3.
2. Preparation of polycarboxylic acid water reducing agent
(1) 150g of isobutylene-based polyoxyethylene polyoxypropylene ether (m: 30, n: 3, average molecular weight 1551.8) synthesized in step 1 was charged into a four-necked flask, 150g of isopentenyl polyoxyethylene ether (average molecular weight 500) was added thereto, and the mixture was heated to 45 ℃ and dissolved with stirring.
(2) 3g of azobisisobutyronitrile is added into the kettle by controlling the temperature at 50 ℃, stirred for 10min, and then a mixed solution (the mass concentration is 98%) comprising 50g of methacrylic acid, 2g of hydroxyethyl acrylate and 4.5g of mercaptoethanol is added dropwise through a single tube at a constant speed for 1.8 h.
(3) After the dropwise addition is finished, continuously curing for 1h, and then cooling to 28 ℃ to prepare the liquid viscosity-reducing polycarboxylate superplasticizer.
(4) And (3) adding hydroxyethyl ethylenediamine into the liquid viscosity-reducing polycarboxylate superplasticizer for neutralization, and adjusting the pH to 7 to obtain the viscosity-reducing polycarboxylate superplasticizer with the effective concentration of 100%.
Example 3
The embodiment provides a synthesis method of a polycarboxylate superplasticizer, which specifically comprises the following steps:
1. preparation of Isopentenyl polyoxyethylene polyoxypropylene Ether
(1) 100g of prenol and 0.30g of KOH were added to a reaction vessel, and the atmosphere in the vessel was replaced with nitrogen.
(2) When the temperature of the kettle rises to 100-110 ℃, starting to introduce 1395g of ethylene oxide and 1300g of propylene oxide, keeping the polymerization temperature at 100-110 ℃ and the reaction pressure at 0.35Mpa, and curing for 3 hours to obtain the reaction product containing the isopentenyl polyoxyethylene polyoxypropylene ether.
(3) The reaction product was neutralized and degassed in a reactor to obtain isopentenyl polyoxyethylene polyoxypropylene ether having an average molecular weight of 2192.62, where m is 35 and n is 10.
2. Preparation of polycarboxylic acid water reducing agent
(1) 270g of the prenylpolyoxyethylene polyoxypropylene ether (m: 35, n: 10, average molecular weight 2192.62) synthesized in step 1 was charged into a four-necked flask, and 67.5g of prenylpolyoxyethylene ether (average molecular weight 600) was added thereto, and the mixture was heated to 60 ℃ and dissolved by stirring.
(2) A total of 2.7g of dimethyl azobisisobutyrate and diisopropyl peroxydicarbonate were added to the reactor while controlling the temperature at 60 ℃ and stirred for 10 minutes, and then a mixed solution (mass concentration: 98%) comprising 40g of maleic acid, 5g of hydroxyethyl methacrylate and 5.4g of mercaptoethanol was added dropwise through a single tube at a constant rate over 2 hours.
(3) After the dropwise addition is finished, continuously curing for 1.2h, and then cooling to 30 ℃ to prepare the liquid viscosity-reducing polycarboxylate superplasticizer.
(4) And (3) adding hydroxyethyl ethylenediamine into the liquid viscosity-reducing polycarboxylate superplasticizer for neutralization, and adjusting the pH to 6.5 to obtain the viscosity-reducing polycarboxylate superplasticizer with the effective concentration of 100%.
Example 4
The embodiment provides a synthesis method of a polycarboxylate superplasticizer, which specifically comprises the following steps:
1. preparation of isobutylene-based polyoxyethylene polyoxypropylene Ether
(1) A2L reactor was charged with 100g of isobutylene alcohol and 0.25g of KOH base catalyst, and the atmosphere in the reactor was replaced with nitrogen.
(2) And (3) when the temperature of the kettle rises to 100-110 ℃, introducing 1620g of ethylene oxide and 610g of propylene oxide, keeping the polymerization reaction temperature at 100 ℃, and curing for 3 hours under the reaction pressure of 0.25Mpa to obtain a reaction product containing the isobutylene polyoxyethylene polyoxypropylene ether.
(3) The reaction product was neutralized and then degassed in the reactor to obtain an isobutylene polyoxyethylene polyoxypropylene ether having an average molecular weight of 2316.68, wherein m is 50 and n is 1.
2. Preparation of polycarboxylic acid water reducing agent
(1) 180g of isobutylene-based polyoxyethylene polyoxypropylene ether (m: 50, n: 1, average molecular weight 2316.68) synthesized in step 1 was charged into a four-necked flask, and 120g of isopentenyl polyoxyethylene ether (average molecular weight 600) was added thereto, and the mixture was heated to 40 ℃ and dissolved with stirring.
(2) 2g of dimethyl azobisisobutyrate was added to the kettle while controlling the temperature at 40 ℃ and stirred for 10min, and then a mixed solution (mass concentration: 98%) comprising 40g of acrylic acid, 5g of hydroxypropyl acrylate and 1.8g of mercaptoethanol was added dropwise through a single tube at a constant rate over 2 hours.
(3) After the dropwise addition is finished, continuously curing for 1.5h, and then cooling to 30 ℃ to prepare the liquid viscosity-reducing polycarboxylate superplasticizer.
(4) And (3) adding hydroxyethyl ethylenediamine into the liquid viscosity-reducing polycarboxylate superplasticizer for neutralization, and adjusting the pH to 6 to obtain the viscosity-reducing polycarboxylate superplasticizer with the effective concentration of 100%.
Detection example 1
Preparing high-strength concrete according to the C50 concrete preparation proportion shown in Table 1, wherein the air content of the concrete is controlled to be 2.0-2.5%, and the expansion degree of the concrete is controlled to be 500-550 mm; the viscosity of concrete was measured by the inverted slump cone method test with reference to Standard test methods for the Properties of general concrete mixtures (GB/T50080-2016), and the smaller the time taken for the concrete to flow out of the inverted slump cone means the smaller the viscosity of the concrete. The viscosity reducing effect of the polycarboxylic acid water reducing agents synthesized in examples 1 to 4 was examined by comparing commercially available water reducing agents. Among them, the commercial water-reducing agents used as comparison are a viscosity-reducing type polycarboxylate water-reducing agent PJN with a solid content of 40% and a viscosity-reducing type polycarboxylate water-reducing agent PC415 with a solid content of 56%.
TABLE 1 high-strength concrete mix ratio (Kg/m3)
| C50 | Cement | Fly ash (I grade) | Mineral powder | Sand (moisture content 5%) | Small stone | Large stone | Water (W) |
| 384 | 48 | 48 | 715 | 341 | 796 | 139 |
TABLE 2 application Properties of polycarboxylic acid Water reducing agent
As can be seen from the above table, under the condition of controlling the initial working performance of the concrete to be consistent, compared with the commercially available polycarboxylate superplasticizers PCM and PC415, the water reducer prepared by the method of the invention has the advantage that the time for the concrete to flow out of a collapse cylinder is obviously reduced, which shows that the polycarboxylate superplasticizer prepared by the method of the invention can effectively reduce the viscosity of the concrete, the wrapping property of the concrete mixture adopting the water reducer of the invention is obviously better than that of the commercially available viscosity-reducing mother solutions with different solid contents, and the concrete cannot separate bleeding even if being mixed, so that the working performance of the concrete is greatly improved. Therefore, the preparation method provided by the invention effectively reduces the reaction temperature of bulk polymerization, reasonably controls the rate of the bulk polymerization reaction, improves the conversion rate of the polymerization reaction, and finally synthesizes the polycarboxylic acid water reducing agent which is liquid at normal temperature, has the effective concentration of 100% and can efficiently reduce the viscosity. The polycarboxylate superplasticizer solves the problems that the traditional polycarboxylate superplasticizer is easy to be adsorbed by clay to cause overlarge viscosity of concrete mixture and poor fluidity of cement concrete, is beneficial to engineering pumping and high-rise engineering construction of concrete, and is suitable for large-scale industrial popularization and application.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (9)
1. The preparation method of the viscosity-reducing polycarboxylate superplasticizer is characterized by preparing the viscosity-reducing polycarboxylate superplasticizer through bulk polymerization, and specifically comprises the following steps:
(1) mixing polyoxyethylene polyoxypropylene ether and polyoxyethylene ether, controlling the temperature to be 40-60 ℃, uniformly stirring, and then adding an initiator and a mixture of unsaturated carboxylic acid, unsaturated carboxylic acid hydroxyalkyl ester and a chain transfer agent;
in the step (1), the polyoxyethylene polyoxypropylene ether has a structure shown in a formula I,
wherein R is1Is methyl or ethyl, R2Hydrogen or methyl, EO is oxyethylene, PO is oxypropylene; m is 30-50, n is 1-20;
(2) curing for 1-1.5 h after the step (1) is finished, and cooling to prepare the viscosity-reducing polycarboxylate superplasticizer;
the polyoxyethylene polyoxypropylene ether is at least one of isobutylene polyoxyethylene polyoxypropylene ether and isopentenyl polyoxyethylene polyoxypropylene ether, and the molecular weight of the polyoxyethylene polyoxypropylene ether is 1500-2400;
the polyoxyethylene polyoxypropylene ether is prepared by the following method:
mixing unsaturated alcohol serving as an initiator with an alkali catalyst, and adding ethylene oxide and propylene oxide in an oxygen-free environment, wherein the mass ratio of the ethylene oxide to the propylene oxide is 1: (0.1 to 0.3); the unsaturated alcohol and the ethylene oxide are subjected to polymerization reaction with the propylene oxide, the reaction temperature is controlled to be 100-130 ℃, and a reaction product containing unsaturated polyoxyethylene polyoxypropylene ether is prepared;
wherein the unsaturated alcohol is at least one of isobutene alcohol and isopentenol;
the polyoxyethylene ether is isopentenyl polyoxyethylene ether, and the molecular weight of the polyoxyethylene ether is 500-1000.
2. The method according to claim 1, wherein the mixture is added dropwise in a single tube at a constant rate over 1.5 to 2 hours.
3. The method of claim 1, further comprising: and after the viscosity reduction type polycarboxylate superplasticizer is prepared, neutralizing the viscosity reduction type polycarboxylate superplasticizer by using hydroxyethyl ethylenediamine until the pH value is 6-7.
4. The production method according to any one of claims 1 to 3, wherein in the step (1), the ratio of polyoxyethylene polyoxypropylene ether: polyoxyethylene ether: initiator: the mass ratio of the chain transfer agent is 1: (0.25-1) and (0.01-0.03): (0.01-0.03).
5. The production method according to claim 4, wherein the unsaturated carboxylic acid is at least one of acrylic acid, methacrylic acid, itaconic acid, and maleic acid.
6. The method according to claim 4, wherein the unsaturated hydroxyalkyl carboxylate is at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and vinyl acetate.
7. The method according to claim 4, wherein the initiator is at least one of dimethyl azobisisobutyrate, azobisisobutyronitrile, and diisopropyl peroxydicarbonate.
8. The method according to claim 4, wherein the chain transfer agent is mercaptoethanol.
9. The method according to claim 1, wherein the temperature in the step (2) is reduced to a temperature of 30 ℃ or less.
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| CN109021181A (en) * | 2018-08-20 | 2018-12-18 | 四川同舟化工科技有限公司 | A kind of poly carboxylic acid series water reducer and preparation method thereof for having both viscosity reduction and protecting function of collapsing |
| CN111072867A (en) * | 2018-10-18 | 2020-04-28 | 辽宁奥克化学股份有限公司 | Solid polycarboxylic acid water reducing agent and preparation method thereof |
| CN109651566B (en) * | 2018-12-13 | 2022-02-22 | 广东奥克化学有限公司 | Viscosity-reducing polycarboxylate superplasticizer and preparation method thereof |
| CN109721722B (en) * | 2018-12-25 | 2021-10-29 | 广东红墙新材料股份有限公司 | Viscosity-reducing type polycarboxylate superplasticizer containing double viscosity-reducing functional groups, and preparation method and application thereof |
| CN109734847B (en) * | 2018-12-25 | 2022-01-11 | 河北红墙新材料有限公司 | Viscosity reduction type polycarboxylate superplasticizer containing three viscosity reduction functional groups, and preparation method and application thereof |
| CN109749074B (en) * | 2018-12-25 | 2021-06-18 | 广东红墙新材料股份有限公司 | Alkyl-containing viscosity-reducing polycarboxylate superplasticizer and preparation method and application thereof |
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| CN109776016B (en) * | 2018-12-26 | 2021-07-20 | 广东红墙新材料股份有限公司 | Early-strength viscosity reduction type polycarboxylate superplasticizer containing three viscosity reduction functional groups and preparation method thereof |
| CN109485323B (en) * | 2018-12-26 | 2021-07-23 | 广东红墙新材料股份有限公司 | Application of early-strength viscosity-reduction type polycarboxylate superplasticizer in preparation of precast concrete |
| CN109762114B (en) * | 2018-12-26 | 2021-08-31 | 广东红墙新材料股份有限公司 | Early-strength viscosity-reduction type polycarboxylate superplasticizer containing double viscosity-reduction functional groups and preparation method thereof |
| CN109455975B (en) * | 2018-12-26 | 2021-07-13 | 河北红墙新材料有限公司 | Application of viscosity-reducing type polycarboxylate superplasticizer in preparation of tailing sand concrete |
| CN109749020B (en) * | 2018-12-26 | 2021-11-16 | 广西红墙新材料有限公司 | Alkyl-containing early-strength viscosity-reduction type polycarboxylate superplasticizer and preparation method thereof |
| CN109678403B (en) * | 2018-12-26 | 2021-07-20 | 广西红墙新材料有限公司 | Application of viscosity-reducing polycarboxylic acid water reducer in preparation of C100 concrete |
| CN110885389B (en) * | 2019-12-16 | 2022-04-12 | 云南森博混凝土外加剂有限公司 | Concrete viscosity reducer synthesized by simple method and preparation method thereof |
| CN111116841A (en) * | 2019-12-31 | 2020-05-08 | 陕西友邦新材料科技有限公司 | Viscosity-reducing polycarboxylate superplasticizer mother liquor as well as preparation method and application thereof |
| CN112521045A (en) * | 2020-12-10 | 2021-03-19 | 联泓(江苏)新材料研究院有限公司 | Viscosity-reducing liquid phase composition and preparation method and application thereof |
| CN112724329A (en) * | 2020-12-29 | 2021-04-30 | 江苏尼高科技有限公司 | Viscosity-reducing polycarboxylic acid concrete water reducer and preparation method thereof |
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| CN102206314B (en) * | 2011-04-25 | 2013-01-02 | 武汉格瑞林建材科技股份有限公司 | Polycarboxylic acid and application thereof, and cement water reducing agent containing polycarboxylic acid |
| CN102504239A (en) * | 2011-11-03 | 2012-06-20 | 山西合盛邦砼建材有限公司 | Catalyst for preparing polycarboxylate water reducing agent macromonomer and preparation method thereof |
| CN103865007A (en) * | 2014-03-17 | 2014-06-18 | 南京瑞迪高新技术有限公司 | Preparation method of viscosity-reduction type polycarboxylate water reducer |
| CN104261721B (en) * | 2014-09-22 | 2016-06-29 | 科之杰新材料集团有限公司 | A kind of ethers polycarboxylic acid slump retaining agent and preparation method thereof |
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