A multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry

Abstract

The present invention discloses a multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry, which comprises the following steps: weighing an aerogel precursor, carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol, carbon nanotubes, a dispersant, a coupling agent and a solvent for standby; mixing the dispersant, the coupling agent and the solvent to obtain a mixed solution A, and performing pre-dispersion, and then adding the aerogel precursor into the mixed solution A to obtain a primary sol; adding the carboxymethyl nanocellulose whiskers, the ammonium polyphosphate, the polyethylene glycol and the carbon nanotubes into the primary sol, adjusting to obtain a mixed solution B, and using ultrasonic dispersion to obtain a secondary sol; adjusting the pH value of the secondary sol with sodium hydroxide to obtain a precursor sol, and placing the precursor sol in a vacuum environment to introduce a high-purity gas stream to obtain an aerogel slurry with excellent dispersibility. The present application effectively avoids the phenomenon of stratification and water separation after long-term standing, and improves the solid content and stability of the aerogel slurry.

Description

Technical Field

[0001] The present invention relates to the technical field of aerogel slurry preparation. Specifically, it relates to a multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry. Background Art

[0002] Aerogel is a new type of solid material with a nano-porous structure, having excellent physical and chemical properties such as high porosity, large specific surface area, low density, low thermal conductivity, and low dielectric constant, and is widely used in fields such as heat insulation, adsorption, and catalysis. However, due to the strong hydrophobicity of existing aerogel powders, they are difficult to disperse in aqueous systems, requiring high-speed stirring or long-time dispersion, which easily leads to the destruction of the aerogel structure, thereby reducing its physical and chemical properties. At the same time, the solid content of aerogel slurry is relatively low, and stratification and water separation phenomena will occur after long-term standing, and it needs to be redispersed and stirred during use, which is inconvenient to operate.

[0003] Chinese Patent CN115676839A discloses a preparation process of aerogel slurry. By mixing water and a nano-stabilizer to form a solution, and then adding aerogel powder and a nano-modifier to this solution and stirring to obtain aerogel slurry. This patent solves the problem that hydrophobic aerogel powder is difficult to disperse in aqueous systems during use. Chinese Patent CN117430372A discloses a dispersible aerogel particle and its preparation method, including dissolving a dispersant and a wetting agent in water to form a dispersion liquid, then adding aerogel powder, a silane coupling agent, and polyphosphoric acid amine to react, and finally granulating and drying to obtain dispersible aerogel particles. The aerogel particles prepared by this patent have a hydrophobic inner layer and a hydrophilic outer layer and have good dispersibility in aqueous systems. It can be found that although the existing technology has certain optimization for the dispersion of aerogel powder when used in aqueous systems, the influence of the use of various additives on the stability and compatibility of aerogel slurry needs to be further improved, and the relevant preparation process steps, process conditions, etc. limit the preparation efficiency and product quality of aerogel particles. To solve the above problems, it is urgent to develop a method for efficiently and high-quality preparing aerogel slurry, enabling aerogel to be well dispersed in aqueous systems, improving the solid content and stability of aerogel slurry, avoiding stratification and water separation phenomena, and thus improving the application convenience of aerogel slurry. Summary of the Invention

[0004] In view of the above technical problems in the related art, the present invention provides a multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry, which can solve the above problems.

[0005] To achieve the above technical purpose, the technical solution of the present invention is realized as follows:

[0006] A multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry includes the following steps:

[0007] S1. Weigh the aerogel precursor, carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol, carbon nanotubes, dispersant, and coupling agent respectively according to the mass ratio of aerogel precursor:carboxymethyl nanocellulose whiskers:ammonium polyphosphate:polyethylene glycol:carbon nanotubes:dispersant:coupling agent = 100:2 - 5:1 - 3:0.8 - 1.5:0.3 - 0.7:0.5 - 1:0.3 - 0.5 for standby, and measure the solvent according to the mass - volume ratio of aerogel precursor:solvent = 1g:20 - 30ml for standby;

[0008] S2. Mix the dispersant, coupling agent and the solvent, and adjust its pH value to 3 - 4 with 0.1mol / L hydrochloric acid to obtain the mixed solution A. Then, pre - disperse the mixed solution A for 10 - 20min under the condition of a shear rate of 100 - 500rpm, and then add the aerogel precursor to the mixed solution A to obtain the primary sol;

[0009] S3. Add the carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol and carbon nanotubes to the primary sol obtained in S2, and adjust its pH value to 7 - 8 with 0.1mol / L sodium hydroxide solution to obtain the mixed solution B. Then, simultaneously use ultrasonic dispersion for the mixed solution B under the condition of a shear rate of 1000 - 2000rpm to obtain the secondary sol;

[0010] S4. Adjust the pH value of the secondary sol obtained in S3 to 10 - 11 with 0.1mol / L sodium hydroxide solution to obtain the precursor sol. Place the precursor sol in a vacuum environment with a vacuum degree of 0.03 - 0.05MPa, and then introduce a high - purity gas flow into the precursor sol under the condition of a shear rate of 1000 - 1500rpm to obtain the aerogel slurry with excellent dispersibility.

[0011] Further, after adding the aerogel precursor to the mixed solution A in S2, it is necessary to continue dispersing for 10 - 20min under the condition of a shear rate of 500 - 800rpm to obtain the primary sol.

[0012] Further, in S3, the ultrasonic frequency is 50kHz, the ultrasonic power is 800W, and ultrasonic dispersion for 20 - 30min is required to obtain the secondary sol.

[0013] Further, in S3, the gas flow rate of the high - purity gas flow is 0.3 - 0.5L / min, and the introduction time of the high - purity gas flow lasts for 10 - 20min.

[0014] Further, the dispersant is any one of sodium oleate, sodium polyacrylate, and polyethylene glycol - polyacrylate copolymer.

[0015] Furthermore, the coupling agent is any one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0016] Furthermore, the solvent is water and ethanol.

[0017] Furthermore, the volume ratio of water to ethanol in the solvent is 1:3 - 5.

[0018] Furthermore, the aerogel precursor is any one or two of tetramethoxysilane (TMOS), tetraethyl orthosilicate (TEOS), polysiloxane (PEDS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), and dimethyldiethoxysilane (DDS).

[0019] Furthermore, the high-purity gas flow is any one of high-purity carbon dioxide, high-purity nitrogen, or high-purity argon.

[0020] Advantages of the present invention: By chemical modification, the surface of the hydrophobic aerogel powder is hydrophilized. Meanwhile, by combining physical means of shear dispersion and ultrasonic dispersion, the dispersibility of the aerogel in the aqueous system is improved, avoiding the problem of aerogel structure damage caused by high-speed stirring or long-time dispersion, thus maintaining the excellent physical and chemical properties of the aerogel. By combining gradient dispersion and chemical coupling, the aerogel particles form a stable three-dimensional network structure with water molecules, effectively avoiding the phenomenon of layering and water separation after long-term standing, improving the solid content and stability of the aerogel slurry, and making it more convenient and fast to use. By using dispersants, coupling agents, carboxymethyl cellulose nanocrystals, ammonium polyphosphate, polyethylene glycol, carbon nanotubes, etc., during the gradient dispersion of the aerogel precursor, the siloxane groups react with the hydroxyl groups on the surface of the aerogel precursor, and at the same time, the polymer segments form physical entanglements with carboxymethyl cellulose nanocrystals and ammonium polyphosphate, realizing the synergistic effect of multi-phase interface chemical bonding and physical cross-linking, significantly enhancing the stability and compatibility of the aerogel slurry. The preparation process of the present invention is simple, the conditions are mild, the cost is low, it can prepare aerogel slurry with good dispersibility efficiently and with high quality, there is no generation of three wastes during the preparation process, meeting the requirements of green and sustainable development, and it can be promoted to industrial production, having significant economic benefits. Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Figure 1 It is a flowchart of a multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to an embodiment of the present invention. Specific embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0025] As Figure 1 shown, a multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry is disclosed according to the present invention, including the following steps:

[0026] S1. Weigh the aerogel precursor, carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol, carbon nanotubes, dispersant, and coupling agent respectively for standby according to the mass ratio of aerogel precursor: carboxymethyl nanocellulose whiskers: ammonium polyphosphate: polyethylene glycol: carbon nanotubes: dispersant: coupling agent = 100: 2-5: 1-3: 0.8-1.5: 0.3-0.7: 0.5-1: 0.3-0.5, and measure the solvent for standby according to the mass-volume ratio of aerogel precursor: solvent = 1 g: 20-30 ml;

[0027] S2. Mix the dispersant, coupling agent and solvent, and adjust its pH value to 3-4 with hydrochloric acid with a concentration of 0.1 mol / L to obtain a mixed solution A. Then, pre-disperse the mixed solution A for 10-20 min under the condition of a shear rate of 100-500 rpm, and then add the aerogel precursor to the mixed solution A to obtain a primary sol;

[0028] S3. Add the carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol and carbon nanotubes to the primary sol obtained in S2, and adjust its pH value to 7-8 with a sodium hydroxide solution with a concentration of 0.1 mol / L to obtain a mixed solution B. Then, ultrasonically disperse the mixed solution B under the condition of a shear rate of 1000-2000 rpm to obtain a secondary sol;

[0029] S4. Adjust the pH value of the secondary sol obtained in S3 to 10 - 11 with a 0.1 mol / L sodium hydroxide solution to obtain a precursor sol. Place the precursor sol in a vacuum environment with a vacuum degree of 0.03 - 0.05 MPa, and then introduce a high-purity gas stream into the precursor sol under the condition of a shear rate of 1000 - 1500 rpm to obtain an aerogel slurry with excellent dispersibility. Example 1:

[0030] Mix 0.48 g of sodium polyacrylate, 0.27 g of silane coupling agent KH560 with 1.8 L of water / ethanol solvent (the volume ratio of water to ethanol is 1:3), and adjust its pH value to 3.8 with a 0.1 mol / L hydrochloric acid to obtain a mixed solution A. Then pre-disperse the mixed solution A for 14 min under the condition of a shear rate of 180 rpm. Then add 70 g of tetraethyl orthosilicate to the mixed solution A, and continue to disperse for 13 min under the condition of a shear rate of 550 rpm to obtain a primary sol. Add 2.16 g of carboxymethyl cellulose nanowhiskers, 1.38 g of ammonium polyphosphate, 0.72 g of polyethylene glycol, and 0.34 g of carbon nanotubes to the primary sol, and adjust its pH value to 7.6 with a 0.1 mol / L sodium hydroxide solution to obtain a mixed solution B. Then simultaneously use ultrasonic dispersion for the mixed solution B under the condition of a shear rate of 1500 rpm, with an ultrasonic frequency of 50 kHz and an ultrasonic power of 800 W, and disperse for 26 min to obtain a secondary sol. Adjust the pH value of the secondary sol to 10.3 with a 0.1 mol / L sodium hydroxide solution to obtain a precursor sol. Place the precursor sol in a vacuum environment with a vacuum degree of 0.04 MPa, and then introduce a high-purity carbon dioxide gas stream into the precursor sol under the condition of a shear rate of 1400 rpm, with a gas flow rate of 0.35 L / min, for 12 min to obtain an aerogel slurry with excellent dispersibility. Example 2:

[0031] 0.82 g of polyethylene glycol-polyacrylate copolymer, 0.47 g of silane coupling agent KH570 and 3.2 L of water / ethanol solvent (volume ratio of water to ethanol is 1:4) were mixed, and the pH value was adjusted to 3.4 with 0.1 mol / L hydrochloric acid to obtain mixture A. Subsequently, mixture A was pre-dispersed for 17 min under the condition of a shear rate of 350 rpm. Then, a mixture of 120 g of tetraethyl orthosilicate and polysiloxane (mass ratio of tetraethyl orthosilicate to polysiloxane is 2:3) was added to mixture A, and dispersion was continued for 18 min under the condition of a shear rate of 750 rpm to obtain a primary sol. 4.35 g of carboxymethyl cellulose nanocrystals, 3.22 g of ammonium polyphosphate, 1.28 g of polyethylene glycol, and 0.63 g of carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.3 with 0.1 mol / L sodium hydroxide solution to obtain mixture B. Subsequently, mixture B was ultrasonically dispersed simultaneously under the condition of a shear rate of 1400 rpm, with an ultrasonic frequency of 50 kHz and an ultrasonic power of 800 W. After dispersion for 22 min, a secondary sol was obtained. The pH value of the secondary sol was adjusted to 10.5 with 0.1 mol / L sodium hydroxide solution to obtain a precursor sol. The precursor sol was placed in a vacuum environment with a vacuum degree of 0.05 MPa. Subsequently, high-purity nitrogen gas flow was introduced into the precursor sol under the condition of a shear rate of 1200 rpm, with a gas flow rate of 0.42 L / min, for 16 min, and an aerogel slurry with excellent dispersibility was obtained. Example 3:

[0032] 0.76 g of sodium oleate, 0.35 g of silane coupling agent KH550 and 2.4 L of water / ethanol solvent (volume ratio of water to ethanol is 1:3) were mixed, and the pH value was adjusted to 3.2 using 0.1 mol / L hydrochloric acid to obtain mixture A. Subsequently, mixture A was pre-dispersed for 12 min under the condition of a shear rate of 200 rpm. Then, 90 g of methyl orthosilicate was added to mixture A, and dispersion was continued for 16 min under the condition of a shear rate of 600 rpm to obtain a primary sol. 3.75 g of carboxymethyl nanocellulose whiskers, 2.46 g of ammonium polyphosphate, 1.16 g of polyethylene glycol, and 0.57 g of carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.2 using 0.1 mol / L sodium hydroxide solution to obtain mixture B. Subsequently, mixture B was simultaneously ultrasonically dispersed under the condition of a shear rate of 1700 rpm, with an ultrasonic frequency of 50 kHz and an ultrasonic power of 800 W. After dispersion for 25 min, a secondary sol was obtained. The pH value of the secondary sol was adjusted to 10.7 using 0.1 mol / L sodium hydroxide solution to obtain a precursor sol. The precursor sol was placed in a vacuum environment with a vacuum degree of 0.04 MPa. Subsequently, a high-purity argon gas stream was introduced into the precursor sol under the condition of a shear rate of 1000 rpm, with a gas flow rate of 0.47 L / min, for 18 min, and an aerogel slurry with excellent dispersibility was obtained. Example 4:

[0033] 1.58 g of sodium polyacrylate, 0.96 g of silane coupling agent KH570 and 5.7 L of water / ethanol solvent (volume ratio of water to ethanol is 1:5) were mixed, and the pH value was adjusted to 3.7 with 0.1 mol / L hydrochloric acid to obtain mixture A. Subsequently, mixture A was pre-dispersed for 16 min under the condition of a shear rate of 400 rpm. Then, 210 g of a mixture of methyl orthosilicate and methyltriethoxysilane (mass ratio of methyl orthosilicate to methyltriethoxysilane is 4:1) was added to mixture A, and dispersion was continued for 12 min under the condition of a shear rate of 650 rpm to obtain a primary sol. 7.64 g of carboxymethyl cellulose nanowhiskers, 4.82 g of ammonium polyphosphate, 2.13 g of polyethylene glycol, and 1.16 g of carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.5 with 0.1 mol / L sodium hydroxide solution to obtain mixture B. Subsequently, mixture B was simultaneously ultrasonically dispersed under the condition of a shear rate of 1600 rpm, the ultrasonic frequency was 50 kHz, the ultrasonic power was 800 W, and after dispersion for 23 min, a secondary sol was obtained. The pH value of the secondary sol was adjusted to 10.6 with 0.1 mol / L sodium hydroxide solution to obtain a precursor sol. The precursor sol was placed in a vacuum environment with a vacuum degree of 0.05 MPa, and then a high-purity carbon dioxide gas stream was introduced into the precursor sol under the condition of a shear rate of 1300 rpm, the gas flow rate was 0.38 L / min, and it was continued for 14 min to obtain an aerogel slurry with excellent dispersibility. Example 5:

[0034] 2.65 g of sodium oleate, 1.36 g of silane coupling agent KH550 and 7.8 L of water / ethanol solvent (volume ratio of water to ethanol is 1:4) were mixed, and the pH value was adjusted to 3.5 with 0.1 mol / L hydrochloric acid to obtain mixture A. Subsequently, mixture A was pre-dispersed for 20 min under the condition of a shear rate of 450 rpm. Then, 300 g of a mixture of methyltrimethoxysilane and dimethyldiethoxysilane (mass ratio of methyltrimethoxysilane to dimethyldiethoxysilane is 3:7) was added to mixture A, and dispersion was continued for 14 min under the condition of a shear rate of 700 rpm to obtain a primary sol. 13.26 g of carboxymethyl nanocellulose whiskers, 5.83 g of ammonium polyphosphate, 3.92 g of polyethylene glycol, and 1.47 g of carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.8 with 0.1 mol / L sodium hydroxide solution to obtain mixture B. Subsequently, mixture B was ultrasonically dispersed under the condition of a shear rate of 1300 rpm, the ultrasonic frequency was 50 kHz, the ultrasonic power was 800 W, and after dispersion for 28 min, a secondary sol was obtained. The pH value of the secondary sol was adjusted to 10.2 with 0.1 mol / L sodium hydroxide solution to obtain a precursor sol. The precursor sol was placed in a vacuum environment with a vacuum degree of 0.03 MPa, and then a high-purity nitrogen gas stream was introduced into the precursor sol under the condition of a shear rate of 1500 rpm, the gas flow rate was 0.46 L / min, and it continued for 15 min to obtain an aerogel slurry with excellent dispersibility.

[0035] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry, characterized in that, It includes the following steps: S1. Weigh the aerogel precursor, carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol, carbon nanotubes, dispersant, and coupling agent respectively for standby according to the mass ratio of aerogel precursor: carboxymethyl nanocellulose whiskers: ammonium polyphosphate: polyethylene glycol: carbon nanotubes: dispersant: coupling agent = 100:2 - 5:1 - 3:0.8 - 1.5:0.3 - 0.7:0.5 - 1:0.3 - 0.

5. And measure the solvent for standby according to the mass - volume ratio of aerogel precursor: solvent = 1g:20 - 30ml; S2. Mix the dispersant, coupling agent with the solvent, and adjust its pH value to 3 - 4 with 0.1mol / L hydrochloric acid to obtain the mixed solution A. Then pre - disperse the mixed solution A for 10 - 20min under the condition of a shear rate of 100 - 500rpm, and then add the aerogel precursor into the mixed solution A to obtain the primary sol; S3. Add the carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol, and carbon nanotubes into the primary sol obtained in S2, and adjust its pH value to 7 - 8 with 0.1mol / L sodium hydroxide solution to obtain the mixed solution B. Then simultaneously use ultrasonic dispersion for the mixed solution B under the condition of a shear rate of 1000 - 2000rpm to obtain the secondary sol; S4. Adjust the pH value of the secondary sol obtained in S3 to 10 - 11 with 0.1mol / L sodium hydroxide solution to obtain the precursor sol. Place the precursor sol in a vacuum environment with a vacuum degree of 0.03 - 0.05MPa. Then introduce a high - purity gas flow into the precursor sol under the condition of a shear rate of 1000 - 1500rpm to obtain an aerogel slurry with excellent dispersibility; The coupling agent is any one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570; the aerogel precursor is any one or two of tetramethoxysilane (TMOS), tetraethyl orthosilicate (TEOS), polysiloxane (PEDS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), and dimethyldiethoxysilane (DDS); 2. The multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to claim 1, wherein After adding the aerogel precursor into the mixed solution A in S2, it is necessary to continue dispersing for 10 - 20min under the condition of a shear rate of 500 - 800rpm to obtain the primary sol; 3. The multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to claim 2, characterized in that: In S3, the ultrasonic frequency is 50kHz, the ultrasonic power is 800W, and ultrasonic dispersion for 20 - 30min obtains the secondary sol; 4. A multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to claim 3, characterized in that: In S3, the gas flow rate of the high - purity gas flow is 0.3 - 0.5L / min, and the introduction time of the high - purity gas flow lasts for 10 - 20min; 5. The multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to claim 1, characterized in that: The dispersant is any one of sodium oleate, sodium polyacrylate, and polyethylene glycol - polyacrylate copolymer; 6. The multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to claim 1, characterized in that: The solvent is water and ethanol; 7. A multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to claim 6, characterized in that: The volume ratio of water to ethanol in the solvent is 1:3 - 5; 8. A multiphase gradient dispersion-chemical coupling method for preparing an aerogel slurry according to claim 1, characterized in that: The high - purity gas flow is any one of high - purity carbon dioxide, high - purity nitrogen, or high - purity argon.

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