Rheological stabilizer and preparation method thereof

Abstract

The invention provides a rheological stabilizer and a preparation method thereof. The rheological stabilizer is prepared by compounding a dispersing agent, an ether internal curing small-molecule polymer, a sacrificial agent and polymeric polyol, and the dispersing agent is prepared by carrying out addition on tiglic acid and epoxide and then polymerizing with an alcohol ether small monomer to prepare a medium-low molecular weight polymer; and the ether internal curing micromolecules and the sacrificial agent are respectively prepared by addition of 3-methyl-2-butene-1-alcohol, 1, 3-dimethyl pentylamine and epoxide. The dispersing agent disclosed by the invention is relatively small in component surface tension, low in foaming power and good in lubricating property; the low molecular weight determines that the seepage force is relatively strong, a stable dispersion effect is provided, and the internal curing small molecules and the sacrificial agent can further improve the stability of the product.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete and relates to a concrete rheological stabilizer, in particular to a rheological stabilizer and a preparation method thereof. Background Art

[0002] Polycarboxylate water reducers disperse cement particles through comb-like structures. The premise of the effect is the adsorption of water reducer molecules and cement particles. Whether the molecular weight of the long side chain of water reducer polyether is reasonable will have a certain impact on cement hydration. With the large-scale application of machine-made sand, concrete is prone to bleeding and segregation, and poor workability. To address this problem, the industry has tried to improve the workability of concrete through substances such as xanthan gum and cellulose ether, but the effect is not good.

[0003] CN105776944A discloses a cement-based rheological stabilizer and its preparation method and use. The stabilizer is compounded by a certain amount of viscosity regulator, retarder, water reducer and defoamer, wherein the viscosity regulator is compounded by high-quality rubber, Brunei rubber and modified bentonite; the retarder is one or more of sodium gluconate, white sugar, citric acid and tartaric acid. When acting on concrete, it can effectively adjust the viscosity of the cement-based system, play the role of preventing sedimentation and water seepage; the compatibility between the components is good, and the workability can be effectively improved.

[0004] CN109516710A discloses a method for preparing an ultra-high performance concrete rheological stabilizer, which adopts a grinding process to modify bentonite with stearate, and then adds lithium salt and white carbon black for uniform mixing. The rheological stabilizer prepared by this method can replace the gel material with equal mass and significantly improve the early anti-disturbance of the concrete mixture.

[0005] Rheological stabilizers are usually used in combination with polycarboxylic acid water reducers. While solving the bleeding phenomenon, it is necessary to consider whether the compatibility between the rheological stabilizer and the water reducer is good. Poor compatibility between the rheological stabilizer and the water reducer may affect its performance. In order to solve the above problem, the present invention prepares a rheological stabilizer by compounding a dispersant, an ether internal curing small molecule polymer, a sacrificial agent and a polymerized polyol, which can significantly improve the workability of concrete and prevent the bleeding phenomenon. Summary of the invention

[0006] The invention provides a rheological stabilizer and a preparation method thereof. The rheological stabilizer provided by the invention has good compatibility with a polycarboxylate water-reducing agent, and multiple polymers synergistically improve the workability of concrete, can effectively prevent water bleeding, and improve the workability of concrete.

[0007] To solve the above problems, the technical solution of the present invention is as follows, and the parts are all parts by mass.

[0008] The rheological stabilizer of the present invention is prepared by compounding the prepared dispersant, ether internal curing small molecule polymer, sacrificial agent and polymerized polyol in a mass ratio of 3:1:1:7;

[0009] The dispersant is prepared by 87.82-155.19 parts of carboxyl heads, 1.0-2.2 parts of catalysts, and 68.28-77.28 parts of cyclic monomers at 140° C., and 5.6-8.6 parts of initiators, 1.2-4.8 parts of chain transfer agents, and water to prepare a liquid A, and 90.02-153.86 parts of ether substances, 3.2-7.9 parts of reducing agents, and water to prepare a liquid B to prepare the polyether monomer at 55-65° C.; after the reaction, the obtained;

[0010] The ether internal curing small molecule polymer is obtained by polymerizing 49.06 to 84.33 parts of alcohol head, 1.0 to 2.2 parts of catalyst, and 215.66 to 250.92 parts of cyclic monomer at 110-120°C;

[0011] The sacrificial agent is obtained by reacting 118.56-170.00 parts of amine heads and 130.00-181.32 parts of cyclic monomers at 165-170°C.

[0012] The preparation method of the rheological stabilizer of the present invention is as follows:

[0013] (1) Preparation of dispersant

[0014] Step 1: Add 87.82-155.19 parts of carboxyl head and 1.0-2.2 parts of catalyst into the autoclave, replace with nitrogen several times, start to evacuate to the gauge pressure -0.1MPa, then heat to 130-140°C and keep for 60min, then heat to 140°C and maintain this temperature, keep the reaction pressure at 0.3MPa by controlling the introduction rate of cyclic monomer, stop feeding when the total amount of cyclic monomer introduced is 68.28-77.28 parts, perform aging reaction at 140°C until the pressure no longer decreases, perform vacuum treatment at a pressure of -0.09MPa for 30min, then reduce the temperature to 40°C and discharge to obtain a polyether monomer;

[0015] Step 2: Add the prepared polyether monomer to the reaction kettle, heat it to 55-65°C in a water bath and keep it warm; prepare 5.6-8.6 parts of initiator, 1.2-4.8 parts of chain transfer agent and water to make liquid A; prepare 90.02-153.86 parts of ether substance, 3.2-7.9 parts of reducing agent and water to make liquid B; drip liquid A and liquid B at the same time, wherein liquid A is dripped for 2-2.5 hours and liquid B is dripped for 1.5-2 hours; keep the temperature for 1 hour after the dripping of liquid A, add 5.9-9.4 parts of neutralizer at one time and add water to 1000 parts to obtain a dispersant mother liquor with a concentration of 30%. The several parts of polyether monomer prepared in step 1 are adjusted in a certain proportion according to the required amount in step 2, so as to control the concentration of the dispersant mother liquor obtained by the reaction to be always controlled at 30%, which reduces the workload for subsequent compounding and other work.

[0016] (2) Preparation of ether-based internal curing small molecule polymers

[0017] Add 49.06-84.33 parts of alcohol head and 1.0-2.2 parts of catalyst into the high-pressure reactor, replace with nitrogen several times, start to evacuate to the gauge pressure of -0.1MPa, then heat to 120-130°C and start dehydration for 1-2h, then cool to 115°C and start to continuously and uniformly introduce 215.66-250.92 parts of cyclic monomers, control the pressure to be less than 0.4MPa, keep warm at 110-120°C for 1.5-2.5h to react to negative pressure, cool and discharge, add 11.9-13.4 parts of neutralizer at one time and add water to 1000 parts to obtain ether-based internal protection small molecule polymer mother liquor with a concentration of 30%.

[0018] (3) Preparation of sacrificial agent

[0019] 118.56-170.00 parts of amine heads are added to the autoclave, and the temperature is raised to 160-170°C while vacuuming. The pressure in the autoclave is 0.2-0.3MPa. The materials in the autoclave are sucked out from the autoclave and then sprayed from the top of the autoclave. At the same time, cyclic monomers are added. After a period of circulation, the autoclave is kept warm and cooled to 90-100°C. Catalysts are added and replaced with nitrogen to start vacuuming to a gauge pressure of -0.1MPa, and then the temperature is raised to 165-170°C. The remaining cyclic monomers are introduced into the autoclave, and 130.00-181.32 parts of cyclic monomers are introduced into the autoclave. The pressure is controlled to be less than 0.4MPa. After all the cyclic monomers are introduced into the autoclave, the circulating spray is maintained for 2.0-2.5h. After the reaction is completed, the temperature is kept for 1h. 11.9-13.4 parts of neutralizer are added at one time and the water is added to 1000 parts to obtain a sacrificial agent mother liquor with a concentration of 30%.

[0020] (4) Preparation of rheological stabilizer

[0021] Several portions of the prepared dispersant, ether internal curing small molecule polymer and sacrificial agent are compounded with several portions of polymerized polyol in a certain proportion, and water is added to 1000 portions to obtain the rheological stabilizer mother solution with a pure solid content concentration of 50%.

[0022] Preferably, the carboxyl head in the dispersant is tiglic acid; the amine head in the sacrificial agent is 1,3-dimethylpentylamine; and the alcohol head in the ether-based internal curing small molecule polymer is 3-methyl-2-butene-1-ol.

[0023] Preferably, the catalyst is one of sodium hydroxide, potassium hydroxide and sodium methoxide, and sodium methoxide is most preferred.

[0024] Preferably, the cyclic monomer is ethylene oxide.

[0025] Preferably, the initiator is one of ammonium persulfate, diisopropyl peroxydicarbonate, and dihexyl peroxydicarbonate, and ammonium persulfate is most preferred; the chain transfer agent is one of thioglycolic acid, mercaptoethanol, and mercaptopropionic acid, and mercaptoethanol is most preferred; the ether substance is one of diethylene glycol monoallyl ether, propylene glycol monoallyl ether, and poly 1,2-propylene glycol, and poly 1,2-propylene glycol is most preferred.

[0026] Preferably, the reducing agent is sodium hypophosphite; and the neutralizing agent is potassium carbonate.

[0027] Preferably, the alcohol-ether ratio is 0.8:1.

[0028] Preferably, the polymeric polyol is composed of several of ethylene glycol, glycerol, trimerpropylene glycol and triethanolamine.

[0029] Preferably, the mass ratio of the dispersant, the ether internal curing small molecule polymer, the sacrificial agent and the polymerized polyol is 3:1:1:7.

[0030] The present invention is based on the functional design of polymers based on the reaction between the terminal carboxyl group of the acid head and the epoxy monomer. The acid head and the epoxy group are etherified to prepare a low molecular weight polyether of about 12000 to 14000. The epoxy material is ethylene oxide, which is compounded with poly 1,2-propylene glycol to prepare a dispersant component: it has a small surface tension, low foaming power, and good lubrication performance; the low molecular weight determines that it has a strong penetration and provides a stable dispersion effect.

[0031] 3-Methyl-2-butene-1-ol reacts with ethylene oxide to prepare an internal curing small molecule polymer, which has good liquid absorption capacity and can form a stable hydration layer in concrete to improve dispersibility; as a non-ionic polymer, it is not affected by other substances in concrete during use and has good stability. 1,3-Dimethylpentylamine and ethylene oxide are used to prepare amine ether sacrificial agents. Compared with alcohol ethers, amine ethers can reduce the negative impact of clay impurities in concrete on strength due to the lone pair of electrons of nitrogen atoms and the electronegativity of oxygen atoms; amine ethers usually have good solubility and can dissolve many organic and inorganic substances. Internal curing small molecules and sacrificial agents are adsorbed before dispersants, which can provide a good adsorption environment for dispersants. After all, clay impurities affect the effect of dispersants.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. The dispersing component of the rheological stabilizer provided by the present invention is prepared by preparing a low molecular weight polyether from tiglic acid and ethylene oxide and compounding it with poly 1,2-propylene glycol. The high side chain density in the dispersant structure enables it to have good dispersing properties.

[0034] 2. The internal curing component provided by the present invention has a small polymer molecular weight and high compatibility with other components; the alcohol head and epoxide addition are used to provide a good water retention effect and prevent the concrete from reducing its strength due to self-shrinkage.

[0035] 3. The sacrificial agent in the gel reducer provided by the present invention has a small molecular weight and contains an amine group at the chain end, which can be adsorbed with clay. At the same time, the chain segment extends between layers to prevent the influence of clay on the performance of concrete. DETAILED DESCRIPTION

[0036] The applicant will further explain the technical solutions and beneficial effects of the present invention in detail in conjunction with specific embodiments, but it should be understood that the following embodiments should not be construed as limiting the scope of protection requested by the claims of this application to any extent.

[0037] The products of the present invention (Examples 1 to 6) and commercially available rheological stabilizers (Novi RS-01 rheological stabilizer) were prepared into C50 concrete samples. The samples obtained in the examples were tested according to the national standard GB8076-2008 "Concrete Admixtures", with the commercially available rheological agent added at 1.0%, the example added at 0.6% in cement, and PO42.5 Conch cement. The test results are shown in Table 3.

[0038] Table 1 Preparation of rheological stabilizer Raw materials

[0039]

[0040]

[0041] Table 2 Preparation process of rheological stabilizer

[0042]

[0043] Table 3 Rheological stabilizer performance test results

[0044]

[0045]

[0046] According to the above table, the rheological stabilizers provided in Examples 4, 5, and 6 have a significant improvement effect on fluidity, and can significantly improve the workability of the system to achieve a state of no water seepage and no bottoming. The reason is that the amount of initiator used in the preparation of the dispersants in Examples 1, 2, and 3 is slightly low, resulting in a larger molecular conformation of the dispersant, which may have an inhibitory effect on the effect of the polycarboxylate water-reducing agent; the combined use of the rheological stabilizer and the polycarboxylate water-reducing agent can improve a certain early strength, and the improvement in the later strength is more significant than that of the commercially available samples, indicating that the rheological stabilizer provided by the present invention can significantly improve workability, improve fluidity, and increase strength when the polymerization process is reasonable.

[0047] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A rheological stabilizer, characterized in that The prepared dispersant, ether internal curing small molecule polymer, sacrificial agent and polymerized polyol are compounded in a mass ratio of 3:1:1:7, and the following parts are all parts by mass; The dispersant is prepared by 87.82-155.19 parts of carboxyl heads, 1.0-2.2 parts of catalysts, and 68.28-77.28 parts of cyclic monomers at 140° C., and 5.6-8.6 parts of initiators, 1.2-4.8 parts of chain transfer agents, and water to prepare a liquid A, and 90.02-153.86 parts of ether substances, 3.2-7.9 parts of reducing agents, and water to prepare a liquid B to prepare the polyether monomer at 55-65° C.; after the reaction, the obtained; The ether internal curing small molecule polymer is obtained by polymerizing 49.06-84.33 parts of alcohol head, 1.0-2.2 parts of catalyst, and 215.66-250.92 parts of cyclic monomer at 110-120°C; The sacrificial agent is obtained by reacting 118.56-170.00 parts of amine heads and 130.00-181.32 parts of cyclic monomers at 165-170°C.

2. The method for preparing the rheological stabilizer according to claim 1, characterized in that The parts are all parts by mass, comprising the following steps: (1) Preparation of dispersant Step 1: Add 87.82-155.19 parts of carboxyl head and 1.0-2.2 parts of catalyst into the autoclave, replace with nitrogen several times, start to evacuate to the gauge pressure -0.1MPa, then heat to 130-140°C and keep for 60min, then heat to 140°C and maintain this temperature, keep the reaction pressure at 0.3MPa by controlling the introduction rate of cyclic monomer, stop feeding when the total amount of cyclic monomer introduced is 68.28-77.28 parts, perform aging reaction at 140°C until the pressure no longer decreases, perform vacuum treatment at a pressure of -0.09MPa for 30min, then reduce the temperature to 40°C and discharge to obtain a polyether monomer; Step 2: Add the prepared polyether monomer into the reaction kettle, heat it to 55-65°C in a water bath and then keep it warm; prepare liquid A by adding 5.6-8.6 parts of initiator, 1.2-4.8 parts of chain transfer agent and water; prepare liquid B by adding 90.02-153.86 parts of ether substance, 3.2-7.9 parts of reducing agent and water; add liquid A and liquid B at the same time, wherein liquid A is added for 2-2.5 hours and liquid B is added for 1.5-2 hours; after adding liquid A, keep it warm for 1 hour, add 5.9-9.4 parts of neutralizer at one time and add water to 1000 parts to obtain a dispersant mother solution with a concentration of 30wt%; (2) Preparation of ether-based internal curing small molecule polymers Add 49.06-84.33 parts of alcohol head and 1.0-2.2 parts of catalyst into the autoclave, replace with nitrogen several times, start to evacuate to the gauge pressure -0.1MPa, then heat to 120-130°C and start dehydration for 1-2h, then cool to 115°C and start to continuously and uniformly introduce 215.66-250.92 parts of cyclic monomers, control the pressure to be less than 0.4MPa, keep warm at 110-120°C for 1.5-2.5h to react to negative pressure, cool and discharge, add 11.9-13.4 parts of neutralizer at one time and add water to 1000 parts to obtain 30% ether-based internal protection small molecule polymer mother liquor; (3) Preparation of sacrificial agent Add 118.56~170.00 parts of amine head to the autoclave, vacuumize and heat to 160~170℃, the pressure in the autoclave is 0.2~0.3MPa, the materials in the autoclave are sucked out from the autoclave and sprayed from the top of the autoclave, and the cyclic monomer is added at the same time. After a period of circulation, cool to 90~100℃, add the catalyst and replace with nitrogen to start vacuuming to a gauge pressure of -0.1MPa, and then heat to 165~170℃. Start to introduce the remaining cyclic monomer into the autoclave, introduce 130.00~181.32 parts of cyclic monomer into the autoclave, control the pressure to be less than 0.4MPa, keep circulating spray for 2.0~2.5h after all the cyclic monomers are introduced into the autoclave, keep warm for 1h after the reaction is completed, add 11.9~13.4 parts of neutralizer at one time and add water to 1000 parts to obtain a sacrificial agent mother liquor with a concentration of 30wt%.

3. (4) Preparation of rheological stabilizer The prepared dispersant, ether internal curing small molecule polymer, sacrificial agent and polymerized polyol are compounded and water is added to 1000 parts to obtain the rheological stabilizer mother solution with a concentration of 50%. The rheological stabilizer mother solution is diluted at a ratio of 1:29 to obtain the rheological stabilizer working solution, and its usage amount is 0.5%.

4. The method according to claim 1, characterized in that: The carboxyl head in the dispersant is tiglic acid.

5. The method according to claim 1, characterized in that The catalyst is one of sodium hydroxide, potassium hydroxide and sodium methoxide.

6. The method according to claim 1, characterized in that The cyclic monomer is ethylene oxide.

7. The method according to claim 1, characterized in that The initiator is one of ammonium persulfate, diisopropyl peroxydicarbonate and dihexyl peroxydicarbonate; the chain transfer agent is one of thioglycolic acid, mercaptoethanol and mercaptopropionic acid; and the ether substance is one of diethylene glycol monoallyl ether, propylene glycol monoallyl ether and poly(1,2-propylene glycol).

8. The method according to claim 1, characterized in that The reducing agent is sodium hypophosphite; the neutralizing agent is potassium carbonate; the amine head is 1,3-dimethylpentylamine; and the ether internal curing small molecule polymer alcohol head is 3-methyl-2-butene-1-ol.

9. The method according to claim 1, characterized in that: The alcohol-ether ratio is 0.5-1.2:

1.

10. The method according to claim 1, characterized in that The polymeric polyol is composed of several of ethylene glycol, glycerol, trimeryl glycol and triethanolamine.

11. The method according to claim 1, characterized in that: The ratio of the dispersant, the ether internal curing small molecule polymer, the sacrificial agent and the polymerized polyol is 3:1:1:7.

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