Multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry

Abstract

The invention discloses a multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry. The method comprises the following steps: weighing an aerogel precursor, carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol, carbon nanotubes, a dispersing agent, a coupling agent and a solvent for later use; mixing a dispersing agent, a coupling agent and a solvent to obtain a mixed solution A, pre-dispersing, and then adding the aerogel precursor into the mixed solution A to obtain primary sol; adding carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol and carbon nanotubes into the primary sol, adjusting to obtain a mixed solution B, and performing ultrasonic dispersion to obtain secondary sol; the pH value of the secondary sol is adjusted through sodium hydroxide, precursor sol is obtained and placed in a vacuum environment, high-purity gas flow is introduced, and aerogel slurry with excellent dispersity is obtained. The layered water phenomenon generated after long-time standing is effectively avoided, and the solid content and stability of the aerogel slurry are improved.

Description

Technical Field

[0001] The invention relates to the technical field of aerogel slurry preparation, and in particular 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 nanoporous structure. It has excellent physical and chemical properties such as high porosity, large specific surface area, low density, low thermal conductivity and low dielectric constant. It is widely used in thermal insulation, adsorption, catalysis and other fields. However, the existing aerogel powder is difficult to disperse in an aqueous system due to its strong hydrophobicity. It requires high-speed stirring or long-term dispersion, which can easily lead to the destruction of the aerogel structure, thereby reducing its physical and chemical properties. At the same time, the solid content of the aerogel slurry is low, and stratification and dehydration will occur after standing for a long time. It needs to be dispersed and stirred again when used, which is inconvenient to operate.

[0003] Chinese patent CN115676839A discloses a process for preparing aerogel slurry, which is obtained by mixing water and nano-stabilizer to form a solution, and then adding aerogel powder and nano-modifier to the solution and stirring to obtain aerogel slurry. This patent solves the problem that hydrophobic aerogel powder is difficult to disperse in an aqueous system during use. Chinese patent CN117430372A discloses a dispersible aerogel particle and a preparation method thereof, including dissolving a dispersant and a wetting agent in water to form a dispersion, 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 in this patent have a hydrophobic inner layer and a hydrophilic outer layer, and have good dispersibility in an aqueous system. It can be found that although the prior art has a certain optimization for the dispersibility of aerogel powder when used in an aqueous system, the use of multiple additives needs to further improve the stability and compatibility of aerogel slurry, and the relevant preparation process steps, process conditions, etc. limit the preparation efficiency and product quality of aerogel particles. In order to solve the above problems, it is urgent to develop a method for preparing aerogel slurry with high efficiency and high quality, so that the aerogel can be well dispersed in the aqueous system, the solid content and stability of the aerogel slurry can be increased, and the stratification and water separation phenomenon can be avoided, thereby improving the convenience of application of the 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 objectives, the technical solution of the present invention is implemented as follows: A multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry comprises the following steps: S1. According to the mass ratio of aerogel precursor: carboxymethyl nanocellulose whisker: ammonium polyphosphate: polyethylene glycol: carbon nanotube: dispersant: coupling agent = 100: 2-5: 1-3: 0.8-1.5: 0.3-0.7: 0.5-1: 0.3-0.5, respectively weigh aerogel precursor, carboxymethyl nanocellulose whisker, ammonium polyphosphate, polyethylene glycol, carbon nanotube, dispersant, coupling agent for use, and according to the mass volume ratio of aerogel precursor: solvent = 1g: 20-30ml, weigh the solvent for use; S2, mixing the dispersant, coupling agent and solvent, and adjusting the pH value thereof to 3-4 with 0.1 mol / L hydrochloric acid to obtain a mixed solution A, and then pre-dispersing the mixed solution A for 10-20 min at a shear rate of 100-500 rpm, and then adding the aerogel precursor to the mixed solution A to obtain a primary sol; S3, adding carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol and carbon nanotubes to the primary sol obtained in S2, and adjusting the pH value thereof to 7-8 with a sodium hydroxide solution having a concentration of 0.1 mol / L to obtain a mixed solution B, and then dispersing the mixed solution B with ultrasound at a shear rate of 1000-2000 rpm to obtain a secondary sol; S4. Use a sodium hydroxide solution with a concentration of 0.1 mol / L to adjust the pH value of the secondary sol obtained in S3 to 10-11 to obtain a precursor sol, and place the precursor sol in a vacuum environment with a vacuum degree of 0.03-0.05 MPa. Then, a high-purity gas flow is introduced into the precursor sol at a shear rate of 1000-1500 rpm to obtain an aerogel slurry with excellent dispersibility.

[0006] Furthermore, after the aerogel precursor is added to the mixed solution A in S2, it is necessary to continue to disperse for 10 to 20 minutes at a shear rate of 500 to 800 rpm to obtain the primary sol.

[0007] Furthermore, the ultrasonic frequency in S3 is 50 kHz, the ultrasonic power is 800 W, and the ultrasonic dispersion takes 20 to 30 minutes to obtain the secondary sol.

[0008] Furthermore, the gas flow rate of the high-purity gas flow in S3 is 0.3 to 0.5 L / min, and the introduction time of the high-purity gas flow lasts for 10 to 20 minutes.

[0009] Furthermore, the dispersant is any one of sodium oleate, sodium polyacrylate, and polyethylene glycol-polyacrylate copolymer.

[0010] Furthermore, the coupling agent is any one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0011] Furthermore, the solvent is water and ethanol.

[0012] Furthermore, the volume ratio of water to ethanol in the solvent is 1:3-5.

[0013] Furthermore, the aerogel precursor is any one or two of methyl orthosilicate TMOS, ethyl orthosilicate TEOS, polysiloxane PEDS, methyltrimethoxysilane MTMS, methyltriethoxysilane MTES, and dimethyldiethoxysilane DDS.

[0014] Furthermore, the high-purity gas flow is any one of high-purity carbon dioxide, high-purity nitrogen or high-purity argon.

[0015] The beneficial effects of the present invention are as follows: the present invention makes the surface of the hydrophobic aerogel powder hydrophilic by chemical modification, and at the same time combines the physical means of shear dispersion and ultrasonic dispersion to improve the dispersibility of the aerogel in the aqueous system, avoids the problem of aerogel structure destruction caused by high-speed stirring or long-term dispersion, thereby maintaining the excellent physical and chemical properties of the aerogel; the present invention combines gradient dispersion and chemical coupling to form a stable three-dimensional network structure between aerogel particles and water molecules, effectively avoids the stratification and dehydration phenomenon after long-term standing, improves the solid content and stability of the aerogel slurry, and is more convenient and quick to use; the present invention uses a dispersant, a coupling agent, and carboxymethyl nanofibers to form a stable three-dimensional network structure between the aerogel particles and the water molecules, effectively avoids the stratification and dehydration phenomenon after long-term standing, improves the solid content and stability of the aerogel slurry, and is more convenient and quick to use; Cellulose whiskers, ammonium polyphosphate, polyethylene glycol and carbon nanotubes, etc., enable the aerogel precursor to react with the hydroxyl group on the surface of the aerogel precursor through the siloxane group during the gradient dispersion process, and at the same time form physical entanglement with the carboxymethyl nanocellulose whiskers and ammonium polyphosphate through the polymer chain segment, so as to achieve the synergistic effect of multiphase interface chemical bonding and physical crosslinking, and significantly enhance the stability and compatibility of the aerogel slurry. The preparation process of the invention is simple, the conditions are mild, and the cost is low. The aerogel slurry with good dispersibility can be prepared efficiently and with high quality. No three wastes are generated in the preparation process, which meets the requirements of sustainable development of green environmental protection, can be promoted for industrial production, and has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] The present invention will be described in further detail below with reference to the accompanying drawings.

[0018] Figure 1 The present invention is a flowchart of a multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0020] like Figure 1 As shown, according to the present invention, a multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry is disclosed, comprising the following steps: S1. According to the mass ratio of aerogel precursor: carboxymethyl nanocellulose whisker: ammonium polyphosphate: polyethylene glycol: carbon nanotube: dispersant: coupling agent = 100: 2-5: 1-3: 0.8-1.5: 0.3-0.7: 0.5-1: 0.3-0.5, respectively weigh aerogel precursor, carboxymethyl nanocellulose whisker, ammonium polyphosphate, polyethylene glycol, carbon nanotube, dispersant, coupling agent for use, and according to the mass volume ratio of aerogel precursor: solvent = 1g: 20-30ml, weigh the solvent for use; S2, mixing the dispersant, coupling agent and solvent, and adjusting the pH value thereof to 3-4 with 0.1 mol / L hydrochloric acid to obtain a mixed solution A, and then pre-dispersing the mixed solution A for 10-20 min at a shear rate of 100-500 rpm, and then adding the aerogel precursor to the mixed solution A to obtain a primary sol; S3, adding carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol and carbon nanotubes to the primary sol obtained in S2, and adjusting the pH value thereof to 7-8 with a sodium hydroxide solution having a concentration of 0.1 mol / L to obtain a mixed solution B, and then dispersing the mixed solution B with ultrasound at a shear rate of 1000-2000 rpm to obtain a secondary sol; S4. Use a sodium hydroxide solution with a concentration of 0.1 mol / L to adjust the pH value of the secondary sol obtained in S3 to 10-11 to obtain a precursor sol, and place the precursor sol in a vacuum environment with a vacuum degree of 0.03-0.05 MPa. Then, a high-purity gas flow is introduced into the precursor sol at a shear rate of 1000-1500 rpm to obtain an aerogel slurry with excellent dispersibility. Embodiment 1:

[0021] 0.48g sodium polyacrylate, 0.27g silane coupling agent KH560 and 1.8L water / ethanol solvent (volume ratio of water to ethanol is 1:3) were mixed, and the pH value was adjusted to 3.8 with 0.1mol / L hydrochloric acid to obtain mixed solution A. Then, mixed solution A was pre-dispersed for 14 min at a shear rate of 180rpm. Then 70g ethyl orthosilicate was added to mixed solution A, and the primary sol was obtained after further dispersion at a shear rate of 550rpm for 13 min. 2.16g carboxymethyl nanocellulose whiskers, 1.38g ammonium polyphosphate, 0.72g polyethylene glycol, and 0.34g carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.6 with 0.1mol / L sodium hydroxide solution to obtain mixed solution B. Then, ultrasonic dispersion of mixed solution B was performed at a shear rate of 1500 rpm, with an ultrasonic frequency of 50 kHz and an ultrasonic power of 800 W. After dispersion for 26 min, a secondary sol was obtained. A sodium hydroxide solution with a concentration of 0.1 mol / L was used to adjust the pH value of the secondary sol to 10.3 to obtain a precursor sol. The precursor sol was placed in a vacuum environment with a vacuum degree of 0.04 MPa, and then a high-purity carbon dioxide gas flow was introduced into the precursor sol at 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. Embodiment 2:

[0022] 0.82g of polyethylene glycol-polyacrylate copolymer, 0.47g of silane coupling agent KH570 and 3.2L of water / ethanol solvent (the volume ratio of water to ethanol is 1:4) are mixed, and the pH value is adjusted to 3.4 with hydrochloric acid at a concentration of 0.1mol / L to obtain a mixed solution A. Then, the mixed solution A is pre-dispersed for 17min at a shear rate of 350rpm. Then, 120g of a mixture of tetraethyl orthosilicate and polysiloxane (the mass ratio of tetraethyl orthosilicate to polysiloxane is 2:3) is added to the mixed solution A, and the primary sol is obtained after continuing to disperse for 18min at a shear rate of 750rpm. 4.35g of carboxymethyl nanocellulose whiskers, 3.22g of ammonium polyphosphate, 1.28g of polyethylene glycol, and 0.63g of carbon nanotubes are added to the primary sol, and the pH value is adjusted to 7.3 with a sodium hydroxide solution at a concentration of 0.1mol / L to obtain a mixed solution B. Then, ultrasonic dispersion of mixed solution B was performed at 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. A sodium hydroxide solution with a concentration of 0.1 mol / L was used to adjust the pH value of the secondary sol to 10.5 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 nitrogen flow was introduced into the precursor sol at a shear rate of 1200 rpm, with a gas flow rate of 0.42 L / min for 16 min to obtain an aerogel slurry with excellent dispersibility. Embodiment three:

[0023] 0.76g sodium oleate, 0.35g silane coupling agent KH550 and 2.4L water / ethanol solvent (volume ratio of water to ethanol is 1:3) were mixed, and the pH value was adjusted to 3.2 with 0.1mol / L hydrochloric acid to obtain mixed solution A. Then, mixed solution A was pre-dispersed for 12min at a shear rate of 200rpm. Then 90g methyl orthosilicate was added to mixed solution A, and the primary sol was obtained after continuing to disperse for 16min at a shear rate of 600rpm. 3.75g carboxymethyl nanocellulose whiskers, 2.46g ammonium polyphosphate, 1.16g polyethylene glycol, and 0.57g carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.2 with a sodium hydroxide solution at a concentration of 0.1mol / L to obtain mixed solution B. Then, ultrasonic dispersion of mixed solution B was performed at 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. A sodium hydroxide solution with a concentration of 0.1 mol / L was used to adjust the pH value of the secondary sol to 10.7 to obtain a precursor sol. The precursor sol was placed in a vacuum environment with a vacuum degree of 0.04 MPa, and then a high-purity argon gas flow was introduced into the precursor sol at a shear rate of 1000 rpm, with a gas flow rate of 0.47 L / min for 18 min to obtain an aerogel slurry with excellent dispersibility. Embodiment 4:

[0024] 1.58g sodium polyacrylate, 0.96g silane coupling agent KH570 and 5.7L water / ethanol solvent (the volume ratio of water to ethanol is 1:5) were mixed, and the pH value was adjusted to 3.7 with hydrochloric acid at a concentration of 0.1mol / L to obtain a mixed solution A. The mixed solution A was then pre-dispersed for 16min at a shear rate of 400rpm. Then 210g of a mixture of methyl orthosilicate and methyltriethoxysilane (the mass ratio of methyl orthosilicate to methyltriethoxysilane was 4:1) was added to the mixed solution A, and the primary sol was obtained after continuing to disperse for 12min at a shear rate of 650rpm. 7.64g carboxymethyl nanocellulose whiskers, 4.82g ammonium polyphosphate, 2.13g polyethylene glycol, and 1.16g carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.5 with a sodium hydroxide solution at a concentration of 0.1mol / L to obtain a mixed solution B. Then, ultrasonic dispersion of mixed solution B was performed at a shear rate of 1600 rpm, with an ultrasonic frequency of 50 kHz and an ultrasonic power of 800 W. After dispersion for 23 min, a secondary sol was obtained. A sodium hydroxide solution with a concentration of 0.1 mol / L was used to adjust the pH value of the secondary sol to 10.6 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 flow was introduced into the precursor sol at a shear rate of 1300 rpm, with a gas flow rate of 0.38 L / min for 14 min to obtain an aerogel slurry with excellent dispersibility. Embodiment five:

[0025] 2.65g sodium oleate, 1.36g silane coupling agent KH550 and 7.8L water / ethanol solvent (the volume ratio of water to ethanol is 1:4) were mixed, and the pH value was adjusted to 3.5 with hydrochloric acid at a concentration of 0.1mol / L to obtain a mixed solution A. Then, the mixed solution A was pre-dispersed for 20min at a shear rate of 450rpm. Then, 300g of a mixture of methyltrimethoxysilane and dimethyldiethoxysilane (the mass of methyltrimethoxysilane and dimethyldiethoxysilane was 3:7) was added to the mixed solution A, and the primary sol was obtained after continuing to disperse for 14min at a shear rate of 700rpm. 13.26g carboxymethyl nanocellulose whiskers, 5.83g ammonium polyphosphate, 3.92g polyethylene glycol, and 1.47g carbon nanotubes were added to the primary sol, and the pH value was adjusted to 7.8 with a sodium hydroxide solution at a concentration of 0.1mol / L to obtain a mixed solution B. Then, ultrasonic dispersion of mixed solution B was performed at a shear rate of 1300 rpm, with an ultrasonic frequency of 50 kHz and an ultrasonic power of 800 W. After dispersion for 28 min, a secondary sol was obtained. A sodium hydroxide solution with a concentration of 0.1 mol / L was used to adjust the pH value of the secondary sol to 10.2 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 flow was introduced into the precursor sol at a shear rate of 1500 rpm, with a gas flow rate of 0.46 L / min for 15 min to obtain an aerogel slurry with excellent dispersibility.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry, characterized in that: The steps include: S1. According to the mass ratio of aerogel precursor: carboxymethyl nanocellulose whisker: ammonium polyphosphate: polyethylene glycol: carbon nanotube: dispersant: coupling agent = 100: 2-5: 1-3: 0.8-1.5: 0.3-0.7: 0.5-1: 0.3-0.5, respectively weigh aerogel precursor, carboxymethyl nanocellulose whisker, ammonium polyphosphate, polyethylene glycol, carbon nanotube, dispersant, coupling agent for use, and according to the mass volume ratio of aerogel precursor: solvent = 1g: 20-30ml, weigh the solvent for use; S2, mixing the dispersant, coupling agent and solvent, and adjusting the pH value thereof to 3-4 with 0.1 mol / L hydrochloric acid to obtain a mixed solution A, and then pre-dispersing the mixed solution A for 10-20 min at a shear rate of 100-500 rpm, and then adding the aerogel precursor to the mixed solution A to obtain a primary sol; S3, adding carboxymethyl nanocellulose whiskers, ammonium polyphosphate, polyethylene glycol and carbon nanotubes to the primary sol obtained in S2, and adjusting the pH value thereof to 7-8 with a sodium hydroxide solution having a concentration of 0.1 mol / L to obtain a mixed solution B, and then dispersing the mixed solution B with ultrasound at a shear rate of 1000-2000 rpm to obtain a secondary sol; S4. Use a sodium hydroxide solution with a concentration of 0.1 mol / L to adjust the pH value of the secondary sol obtained in S3 to 10-11 to obtain a precursor sol, and place the precursor sol in a vacuum environment with a vacuum degree of 0.03-0.05 MPa. Then, a high-purity gas flow is introduced into the precursor sol at a shear rate of 1000-1500 rpm to obtain an aerogel slurry with excellent dispersibility.

2. The multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry according to claim 1, characterized in that: After the aerogel precursor is added to the mixed solution A in S2, it is necessary to continue dispersing for 10 to 20 minutes at a shear rate of 500 to 800 rpm to obtain the primary sol.

3. The multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry according to claim 2, characterized in that: The ultrasonic frequency in S3 is 50 kHz, the ultrasonic power is 800 W, and the ultrasonic dispersion takes 20 to 30 minutes to obtain the secondary sol.

4. The multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry according to claim 3, characterized in that: The gas flow rate of the high-purity gas flow in S3 is 0.3 to 0.5 L / min, and the high-purity gas flow is introduced for 10 to 20 minutes.

5. The multiphase gradient dispersion-chemical coupling method for preparing 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 aerogel slurry according to claim 1, characterized in that: The coupling agent is any one of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570.

7. The multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry according to claim 1, characterized in that: The solvents are water and ethanol.

8. The multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry according to claim 7, characterized in that: The volume ratio of water to ethanol in the solvent is 1:3-5.

9. The multiphase gradient dispersion-chemical coupling method for preparing aerogel slurry according to claim 1, characterized in that: The aerogel precursor is any one or two of methyl orthosilicate TMOS, ethyl orthosilicate TEOS, polysiloxane PEDS, methyltrimethoxysilane MTMS, methyltriethoxysilane MTES, and dimethyldiethoxysilane DDS.

10. The multiphase gradient dispersion-chemical coupling method for preparing 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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