Enhanced hydrophobic emulsion of pH-complexing response mechanism as well as preparation process and application of enhanced hydrophobic emulsion

Abstract

The invention discloses an enhanced hydrophobic emulsion of a pH-complexing response mechanism as well as a preparation process and application of the enhanced hydrophobic emulsion. The hydrophobic emulsion comprises hydrophobic agent particles which are dispersed in an aqueous emulsion and have a complexing response mechanism, and a nano calcium salt complex which is dissolved in the aqueous emulsion. Wherein the hydrophobic agent particles with the complexing response mechanism comprise a hydrophobic substance inner core and a coating layer formed by hydrophobic modified nano calcium salt solid particles coating the surface of the inner core, and nano calcium salt has the property of being insoluble in water or slightly soluble in water. The nano calcium salt complex is formed by complexing the nano calcium salt and a complexing agent. The hydrophobic emulsion provided by the invention can delay premature release of hydrophobic substances and exert multiple synergistic effects in a decomplexing process, so that the compactness and mechanical strength of a concrete material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete admixtures, and particularly relates to a reinforced hydrophobic emulsion with a pH-complexation response mechanism, its preparation process and application. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Currently, there are mainly two technical paths for optimizing the hydrophobic performance of cement-based materials: one is to introduce organic hydrophobic substances (such as silanes, silicone polymers) into the cement system, and the other is to physically coat the hydrophobic substances with inorganic nanomaterials and then introduce them into the cement system. It should be noted that the hydration reaction mechanism of cement-based materials has significant particularity, which not only includes the physical adsorption of cementitious particles and water medium, but also involves a series of chemical evolution processes such as the formation of ettringite, calcium silicate hydrate, etc. The method of directly adding hydrophobic substances will interfere with the hydration reaction of cement because the hydrophobic substances will adsorb on the surface of unhydrated cement particles, thereby affecting the growth of cement strength and the formation of the final microstructure of cement.

[0004] Although the physical coating method helps to delay the release of the modifier by encapsulating the modifier in some carriers. However, due to the low stability of the coating material itself, especially in the cement hydration process, it is easily affected by environmental factors, resulting in premature rupture or failure of the coating layer. In addition, due to the limited mechanical properties of the coating material, it cannot effectively fill the pores and microcracks inside the concrete material, resulting in obvious deficiencies in improving the strength of cement-based materials by this method, and it is difficult to make up for the decline in the mechanical properties of concrete materials caused by the addition of hydrophobic agents. Summary of the Invention

[0005] In view of the above problems, the present invention provides a reinforced hydrophobic emulsion with a pH-complexation response mechanism, its preparation process and application, which can delay the premature release of hydrophobic substances, and play multiple synergistic effects during the decomplexation process, thereby improving the density and mechanical strength of concrete materials. Specifically, the present invention discloses the following technical solutions.

[0006] First, the present invention discloses a reinforced hydrophobic emulsion with a pH-complexation response mechanism, comprising: hydrophobic agent particles with a complexation response mechanism dispersed in an aqueous emulsion, and a nano-calcium salt complex dissolved in the aqueous emulsion. Among them: the hydrophobic agent particles with a complexation response mechanism include a hydrophobic substance core and a coating layer formed by hydrophobic modified nano-calcium salt solid particles coated on the surface of the core, and the hydrophobic modified nano-calcium salt is a substance modified by a silane coupling agent and insoluble or slightly soluble in water. The nano-calcium salt complex is formed by the complexation reaction of a nano-calcium salt and a complexing agent.

[0007] Further, the hydrophobic substance includes at least one of chlorotrimethylsilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, triisopropylsilane, trimethylethoxysilane, polydimethylsiloxane, polymethylhydrosiloxane, methyltrimethoxysilane, isobutyltriethoxysilane, cetyltrimethoxysilane, etc.

[0008] Further, the nano-calcium salt includes at least one of calcium sulfate, calcium carbonate, calcium oxalate, calcium fluoride, etc.

[0009] Further, the complexing agent includes at least one of triethanolamine, triethylenetetramine, tetrapropylhydroxyethylenediamine, ammonium ethylenediaminetetraacetate, ammonium diethylenetriaminepentaacetate, ammonium ethylene glycol diethylether diaminetetraacetate, ammonium hydroxyethylethylenediaminetriacetate, etc.

[0010] Secondly, the present invention discloses a preparation process of the reinforced hydrophobic emulsion with the pH-complexation response mechanism, comprising the following steps: (1) Add the complexing agent to water and fully dissolve it to form a complexing agent solution, then add an excessive amount of nano-calcium salt and carry out a complexation reaction under stirring conditions. After removing the insoluble substances, a complexation product solution is obtained and reserved.

[0011] (2) Take another nano-calcium salt, add it and a silane coupling agent to an ethanol aqueous solution, react under heating and stirring conditions, separate out the solid product, and obtain hydrophobic modified nano-calcium salt solid particles after drying, and reserve them.

[0012] (3) Add the modified nano-calcium salt and the hydrophobic substance to the complexation product solution and then carry out emulsification treatment to obtain the hydrophobic emulsion after completion.

[0013] Further, in step (1), the concentration of the complexing agent solution does not exceed 0.5 mol / L, preferably 0.2 - 0.5 mol / L.

[0014] Further, in step (1), the time of the complexation reaction is 1 - 5 hours. During this process, the nano-calcium salt and the complexing agent form a complexation product and dissolve into the complexation product solution.

[0015] Furthermore, in step (2), the mass ratio of the nano-calcium salt, silane coupling agent, and ethanol aqueous solution is 1-3: 0.7-1.2: 10. Optionally, the silane coupling agent includes at least one of KH-550, KH-560, KH-570, etc. The mass fraction of the ethanol aqueous solution is 50-60%.

[0016] Furthermore, in step (2), the heating temperature is 70-85 °C, and the reaction time is 1.5-2 hours. During this process, the hydroxyl (-OH) groups on the surface of the nano-calcium salt react with the hydroxyl groups of the silane coupling agent to form chemical bonds to connect the two, enabling the nano-calcium salt to stably exist at the water-oil interface (i.e., the interface of the subsequent hydrophobic substance and complex product solution), facilitating the coating of the hydrophobic substance.

[0017] Furthermore, in step (3), the modified nano-calcium salt is 30-40% of the mass of the complex product solution. The hydrophobic substance is 20-25% of the mass of the complex product solution.

[0018] Furthermore, in step (3), the shear rate of the emulsification treatment is 12000-15000 r / min, and the treatment time is 2-5 min. During this process, the solid particles of the modified nano-calcium salt form a surface coating on the oily microparticles formed by the hydrophobic substance to form a core-shell structure. Then, it jointly forms a hydrophobic emulsion with the complex product solution in which the complex product is dissolved.

[0019] Finally, the present invention discloses the application of the enhanced hydrophobic emulsion with the pH-complexation response mechanism in silicate cement-based materials. Optionally, the dosage of the hydrophobic emulsion is 6-9% of the mass of the cement component in the silicate cement-based materials.

[0020] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: The hydrophobic emulsion of the present invention can not only delay the premature release of hydrophobic substances, but also play a seeding effect during the dissociation process, thereby improving the density and mechanical strength of concrete materials. The reason is as follows: The process adopted in the present invention is to first convert nano-calcium salt solid particles into soluble complexes by using a complexing agent and dissolve them in water, and then use hydrophobic-modified nano-calcium salt solid particles as coating materials to coat the hydrophobic substances. When this hydrophobic emulsion is incorporated into concrete materials, the modified nano-calcium salt coating layer on the surface of the hydrophobic substances can delay the release of the hydrophobic substances, prevent the hydrophobic substances from prematurely intervening in the hydration reaction of cement, resulting in hindrance to the hydration reaction of cement components and affecting the development of mechanical strength. As the hydration reaction proceeds, the pH in the concrete materials gradually decreases, and the complexes of the nano-calcium salts dispersed in the concrete materials gradually begin to dissociate, and then form nano-calcium salts insoluble in water. At the same time, the nano-calcium salts released during the dissociation process aggregate and grow with the solid nano-calcium salts formed after the coating layer of the hydrophobic substances is damaged due to the decrease in environmental pH as the crystal nuclei, forming solid particles to fill the pore microcracks and the like in the concrete materials, thereby improving the density and mechanical strength of the concrete materials. At the same time, because the above dissociation reaction proceeds slowly, it can be well matched with the hydration and hardening process of the concrete materials, and then can fill the microcracks generated due to shrinkage during the hydration and hardening process, thereby contributing to the improvement of the mechanical properties of the concrete materials. Description of the Drawings

[0021] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0022] Figure 1 Sample diagram of the enhanced hydrophobic emulsion with pH-complexing response mechanism prepared for Example 1 below.

[0023] Figure 2 Contact angle test diagram of the specimen prepared for Example 1 below.

[0024] Figure 3 Contact angle test diagram of the specimen prepared for Example 2 below.

[0025] Figure 4 Contact angle test diagram of the specimen prepared for Example 3 below.

[0026] Figure 5 Contact angle test diagram of the specimen prepared for Example 4 below.

[0027] Figure 6 Contact angle test diagram of the specimen prepared for Example 5 below.

[0028] Figure 7Contact angle test diagram of the specimens prepared for Example 6 below.

[0029] Figure 8 Contact angle test diagram of the specimens prepared for Example 7 below. Detailed implementation manners

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions noted in the following embodiments, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0031] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meaning as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be obtained through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in the conventional manner in the art or according to the product instructions.

[0032] In addition, any methods and materials similar or equivalent to the described content can be applied to the method of the present invention. The technical solution of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0033] Example 1 A preparation process of an enhanced hydrophobic emulsion with a pH-complexation response mechanism, comprising the following steps: (1) Add the complexing agent (triethanolamine) to water and fully dissolve it to form a complexing agent solution with a concentration of 0.5 mol / L. Then add an excessive amount of nano-calcium salt (calcium sulfate) and continuously stir for 3 hours for complexation reaction. After completion, filter to remove the undissolved nano-calcium salt to obtain a complexation product solution for standby.

[0034] (2) Take another nano-calcium salt (calcium sulfate), add it and the silane coupling agent (KH-550) to an ethanol aqueous solution with a mass fraction of 50%. The mass ratio of the three is 1:1:10. Then heat to 80 °C and stir for 2 hours. After completion, filter out the solid product and dry it to obtain hydrophobic modified nano-calcium salt solid particles for standby.

[0035] (3) Add 40% of the mass of the modified nano-calcium salt and 20% of chlorotrimethylsilane to the complexation product solution, and then carry out emulsification treatment (shearing rate: 15000 r / min, treatment time: 4 min). After completion, the hydrophobic emulsion is obtained, as Figure 1 shown.

[0036] Performance test: Referring to the standard GB / T 17671-2021 "Test method for strength of cement mortar (ISO method)", the hydrophobic emulsion prepared in this embodiment is added to the cement mortar (the mass ratio of cement (PO 42.5): water: standard sand = 2:1:6, and the hydrophobic emulsion accounts for 7.5% of the mass of cement), stirred evenly, and then poured into the mold, demolded after hardening and forming, and cured under standard conditions for 28 days to obtain the test block. Then the compressive strength of the test block is tested according to the above standard. In addition, an optical contact angle meter (model JC2000D3A) is used to measure the contact angle on the surface of the test block, such as Figure 2 The test results of the above indicators are as follows: 28d compressive strength = 46.36MPa, contact angle = 125°.

[0037] Example 2 A preparation process of a pH-complexation response mechanism reinforced hydrophobic emulsion comprises the following steps: (1) Add the complexing agent (ammonium ethylenediaminetetraacetate) into water and fully dissolve it to form a complexing agent solution with a concentration of 0.3 mol / L, then add an excess of nano calcium salt (calcium carbonate) and stir continuously for 2 hours to carry out complexing reaction. After completion, filter to remove the undissolved nano calcium salt to obtain a complexing product solution for standby use.

[0038] (2) Take another nano calcium salt (calcium carbonate), add it and silane coupling agent (KH-560) to 55% ethanol aqueous solution, the mass ratio of the three is 2:0.7:10. Then heat to 70°C and stir to react for 2 hours. After completion, filter out the solid product, dry it to obtain hydrophobically modified nano calcium salt solid particles, and set aside.

[0039] (3) Adding 30% by weight of the modified nano calcium salt and 20% by weight of 1H,1H,2H,2H-perfluorodecyltriethoxysilane to the complex product solution and then performing emulsification treatment (shear rate of 12000 r / min, treatment time of 5 min), the hydrophobic emulsion is obtained after completion.

[0040] Performance test: The same method as in Example 1 was used to test the 28d compressive strength and contact angle (such as Figure 3 The test results of the above indicators are as follows: 28d compressive strength = 44.27MPa, contact angle = 137°.

[0041] Example 3 A preparation process of a pH-complexation response mechanism reinforced hydrophobic emulsion comprises the following steps: (1) Add the complexing agent (triethylenetetramine) to water and dissolve it thoroughly to form a complexing agent solution with a concentration of 0.2 mol / L. Then add an excessive amount of nano-calcium salt (calcium fluoride) and continuously stir for 1 hour for the complexation reaction. After completion, filter to remove the undissolved nano-calcium salt to obtain a complexation product solution for standby.

[0042] (2) Take another nano-calcium salt (calcium fluoride), add it and the silane coupling agent (KH-570) to an ethanol aqueous solution with a mass fraction of 60%. The mass ratio of the three is 3:1.2:10. Then heat to 85 °C and stir for 1.5 hours. After completion, filter out the solid product, and obtain hydrophobic modified nano-calcium salt solid particles after drying for standby.

[0043] (3) Add 34% of the mass of the modified nano-calcium salt and 20% of isobutyltriethoxysilane to the complexation product solution, and then perform emulsification treatment (shear rate is 15000 r / min, treatment time is 2 min). After completion, obtain the hydrophobic emulsion.

[0044] Performance test: Use the same method as in Example 1 above to test the 28-day compressive strength and contact angle of the cement material-based specimens doped with the hydrophobic emulsion of this example (as Figure 4 shown). The test results of the above indicators are as follows: 28-day compressive strength = 43.78 MPa, contact angle = 135°.

[0045] Example 4 A preparation process of an enhanced hydrophobic emulsion with a pH-complexing response mechanism, comprising the following steps: (1) Add the complexing agent (tetrahydroxypropyl ethylenediamine) to water and dissolve it thoroughly to form a complexing agent solution with a concentration of 0.4 mol / L. Then add an excessive amount of nano-calcium salt (calcium oxalate) and continuously stir for 5 hours for the complexation reaction. After completion, filter to remove the undissolved nano-calcium salt to obtain a complexation product solution for standby.

[0046] (2) Take another nano-calcium salt (calcium oxalate), add it and the silane coupling agent (KH-550) to an ethanol aqueous solution with a mass fraction of 50%. The mass ratio of the three is 2:0.9:10. Then heat to 80 °C and stir for 2 hours. After completion, filter out the solid product, and obtain hydrophobic modified nano-calcium salt solid particles after drying for standby.

[0047] (3) Add 32% of the mass of the modified nano-calcium salt and 20% of polydimethylsiloxane to the complexation product solution, and then perform emulsification treatment (shear rate is 15000 r / min, treatment time is 2 min). After completion, obtain the hydrophobic emulsion.

[0048] Performance test: The 28-day compressive strength and contact angle of the cementitious material specimens doped with the hydrophobic emulsion of this example were tested using the same method as in Example 1 above (as Figure 5 shown). The test results of the above indicators are as follows: 28-day compressive strength = 44.89 MPa, contact angle = 131°.

[0049] Example 5 A preparation process of an enhanced hydrophobic emulsion with a pH-complexation response mechanism includes the following steps: (1) Take nano-calcium salt (calcium sulfate), add it and silane coupling agent (KH-550) to an ethanol aqueous solution with a mass fraction of 50%. The mass ratio of the three is 1:1:10. Then heat to 80 °C and stir for 2 hours. After completion, filter out the solid product, and obtain hydrophobic modified nano-calcium salt solid particles after drying for standby.

[0050] (2) Add 40% of the mass of the modified nano-calcium salt and 20% of chlorotrimethylsilane to clear water, and then perform emulsification treatment (shearing rate is 15000 r / min, treatment time is 4 min). After completion, the hydrophobic emulsion is obtained.

[0051] Performance test: The 28-day compressive strength and contact angle of the cementitious material specimens doped with the hydrophobic emulsion of this example were tested using the same method as in Example 1 above (as Figure 6 shown). The test results of the above indicators are as follows: 28-day compressive strength = 35.17 MPa, contact angle = 121°.

[0052] Example 6 A preparation process of an enhanced hydrophobic emulsion with a pH-complexation response mechanism includes the following steps: (1) Add the complexing agent (ammonium ethylenediaminetetraacetate) to water and fully dissolve it to form a complexing agent solution with a concentration of 0.3 mol / L. Then add an excessive amount of nano-calcium salt (calcium carbonate) and continuously stir for 2 hours for complexation reaction. After completion, filter out the undissolved nano-calcium salt to obtain a complexation product solution for standby.

[0053] (2) Add 30% of the mass of nano-calcium salt (calcium carbonate) and 20% of 1H,1H,2H,2H-perfluorodecyltriethoxysilane to the complexation product solution, and then perform emulsification treatment (shearing rate is 12000 r / min, treatment time is 5 min). After completion, the hydrophobic emulsion is obtained.

[0054] Performance test: The 28-day compressive strength and contact angle of the cementitious material specimens doped with the hydrophobic emulsion of this example were tested using the same method as in Example 1 above (as Figure 7As shown). The test results of the above indicators are as follows: 28-day compressive strength = 38.09 MPa, contact angle = 134°.

[0055] Example 7 A preparation process for an enhanced hydrophobic emulsion with a pH-complexation response mechanism includes the following steps: (1) Add the complexing agent (triethylenetetramine) to water and fully dissolve it to form a complexing agent solution with a concentration of 0.2 mol / L. Then add an excessive amount of nano-calcium salt (calcium fluoride) and continuously stir for 1 hour for complexation reaction. After completion, filter to remove the undissolved nano-calcium salt to obtain a complexation product solution for standby.

[0056] (2) Add a hydrophobic substance (isobutyltriethoxysilane) accounting for 20% of its mass to the complexation product solution, and then perform emulsification treatment (shearing rate is 15000 r / min, treatment time is 2 min). After completion, obtain the hydrophobic emulsion.

[0057] Performance test: Use the same method as in Example 1 above to test the 28-day compressive strength and contact angle of the cement material-based specimens doped with the hydrophobic emulsion of this example (as Figure 8 shown). The test results of the above indicators are as follows: 28-day compressive strength = 30.27 MPa, contact angle = 126°.

[0058] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An enhanced hydrophobic emulsion with a pH-complexation response mechanism, characterized in that, Comprising: Hydrophobic agent particles with a complexation response mechanism dispersed in an aqueous emulsion, the particles comprising: a hydrophobic substance core, and a coating layer formed by hydrophobic modified nano-calcium salt solid particles coated on the surface of the core, wherein the hydrophobic modified nano-calcium salt is a substance modified by a silane coupling agent and insoluble or slightly soluble in water; And, a nano-calcium salt complex dissolved in the aqueous emulsion, which is formed by a nano-calcium salt and a complexing agent through a complexation reaction.

2. The enhanced hydrophobic emulsion with a pH-complexation response mechanism according to claim 1, wherein The hydrophobic substance includes at least one of chlorotrimethylsilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, triisopropylsilane, trimethylethoxysilane, polydimethylsiloxane, polymethylhydrosiloxane, methyltrimethoxysilane, isobutyltriethoxysilane, hexadecyltrimethoxysilane.

3. The enhanced hydrophobic emulsion with a pH-complexation response mechanism according to claim 1, characterized in that, The nano-calcium salt includes at least one of calcium sulfate, calcium carbonate, calcium oxalate, calcium fluoride.

4. The enhanced hydrophobic emulsion with a pH-complexation response mechanism according to any one of claims 1-3, characterized in that, The complexing agent includes at least one of triethanolamine, triethylenetetramine, tetra-hydroxypropyl ethylenediamine, ammonium ethylenediaminetetraacetate, ammonium diethylenetriaminepentaacetate, ammonium ethylene glycol diethylether diaminetetraacetate, ammonium hydroxyethyl ethylenediaminetriacetate.

5. The preparation process of the enhanced hydrophobic emulsion with a pH-complexation response mechanism according to any one of claims 1-4, characterized in that, Including the following steps: (1) Adding the complexing agent to water and fully dissolving it to form a complexing agent solution, then adding an excessive amount of nano-calcium salt and carrying out a complexation reaction under stirring conditions, and removing the insoluble matter to obtain a complexation product solution for standby; (2) Separately taking nano-calcium salt, adding it and a silane coupling agent to an ethanol aqueous solution, reacting under heating and stirring conditions, separating out the solid product, and drying to obtain hydrophobic modified nano-calcium salt solid particles for standby; (3) Adding the modified nano-calcium salt and the hydrophobic substance to the complexation product solution and then carrying out emulsification treatment to obtain the hydrophobic emulsion after completion.

6. The preparation process of the enhanced hydrophobic emulsion with a pH-complexation response mechanism according to claim 5, characterized in that, In step (1), the concentration of the complexing agent solution does not exceed 0.5 mol / L.

7. The preparation process of the enhanced hydrophobic emulsion with a pH-complexation response mechanism according to claim 5, characterized in that, In step (1), the time of the complexation reaction is 1 to 5 hours.

8. The preparation process of the enhanced hydrophobic emulsion with a pH-complexation response mechanism according to claim 5, characterized in that, In step (2), the mass ratio of the nano-calcium salt, the silane coupling agent, and the ethanol aqueous solution is 1 to 3: 0.7 to 1.2: 10; Optionally, in step (2), the silane coupling agent includes at least one of KH-550, KH-560, KH-570; Optionally, in step (2), the mass fraction of the ethanol aqueous solution is 50 to 60%; Optionally, in step (2), the heating temperature is 70 to 85 °C, and the reaction time is 1.5 to 2 hours.

9. The preparation process of the enhanced hydrophobic emulsion with a pH-complexing response mechanism according to any one of claims 5-8, characterized in that, In step (3), the modified nano-calcium salt is 30 to 40% of the mass of the complexation product solution; the hydrophobic substance is 20 to 25% of the mass of the complexation product solution; Optionally, in step (3), the shear rate of the emulsification treatment is 12000 to 15000 r / min, and the time is 2 to 5 min.

10. Application of the enhanced hydrophobic emulsion with a pH-complexation response mechanism according to any one of claims 1-4, or the hydrophobic emulsion obtained by the preparation process according to any one of claims 5-8 in a Portland cement-based material; optionally, the dosage of the hydrophobic emulsion is 6 to 9% of the mass of the cement component in the Portland cement-based material.

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