Aerogel water-based thermal insulation coating and preparation method thereof

Abstract

The invention discloses an aerogel water-based heat insulation coating and a preparation method thereof, belongs to the technical field of coating preparation, and aims to solve the technical problem that the heat insulation performance and the wear resistance of a water-based coating in the prior art need to be further improved. The aerogel-containing waterborne heat insulation coating is prepared from the following raw materials in parts by weight: 70 to 80 parts of modified polyurethane, 10 to 12 parts of hydrophilic aerogel, 8 to 10 parts of modified chain extender and 27 to 36 parts of auxiliary materials, by introducing the modified chain extender, the cross-linking density and char forming capacity of the coating are improved, and the mechanical and flame-retardant properties are enhanced; the hydrophilic aerogel constructs a stable and continuous porous framework, the heat insulation property is improved, and the inner composite glass fiber powder forms a three-dimensional supporting structure, so that the wear resistance and the structural stability are remarkably improved; the modified polyurethane forms a target functional group end cap through chain segment optimization, the dispersing performance of the hydrophilic aerogel is improved, and finally, the high-performance water-based thermal insulation coating is obtained through synergistic cooperation of the three functional components.

Description

Technical Field

[0001] The present invention relates to the technical field of coating preparation, and in particular to an aerogel water-based thermal insulation coating and a preparation method thereof. Background Art

[0002] Aerogel water-based thermal insulation coating is an emerging high-performance energy-saving material in recent years. It combines the excellent thermal insulation performance of aerogel with the environmental protection characteristics of water-based coatings and is widely used in construction, industry and other fields. In terms of thermal insulation, aerogel has ultra-low thermal conductivity, and its porous structure can effectively block heat conduction. Compared with traditional coatings, it significantly reduces the surface temperature of the substrate and reduces energy consumption. In terms of UV resistance, aerogel itself has strong UV resistance. When combined with functional additives such as nano-titanium dioxide and zinc oxide, the coating's anti-aging and weather resistance are further enhanced. In the early stages of development, due to cost and preparation technology, aerogel coatings are mostly in the experimental and small-scale application stage. With the advancement of material modification technology and the promotion of environmental protection policies, aerogel water-based coatings have gradually been industrialized and become one of the important choices for building energy conservation and green coatings, showing broad development prospects.

[0003] Prior art CN107266997B discloses an aerogel water-based thermal insulation coating and a preparation method thereof. The coating is mainly composed of a water-based resin and aerogel powder. The aerogel powder consists of an internal hydrophobic layer and a surface hydrophilic layer. The thickness of the surface hydrophilic layer is 0.1-100 μm. The preparation method of an aerogel water-based thermal insulation coating of this invention comprises the following steps: (1) modifying the aerogel powder; (2) mixing the aerogel powder of step (1) with the water-based resin, stirring or ball milling; this invention adds aerogel powder to the water-based coating system to ensure that the nanoporous structure of the aerogel is not destroyed and give full play to the thermal insulation and heat preservation performance of the aerogel. The preparation process of the aerogel water-based thermal insulation coating provided by this invention is simple, practical, has excellent performance, is low in price, and is suitable for industrial production.

[0004] However, the above invention obtains a water-based thermal insulation coating by adding aerogel powder to a water-based coating system, which realizes functional regulation of the aerogel surface by first hydrophobic and then hydrophilic treatment. The hydrophobic modification improves the hydrophobicity of the aerogel, but the subsequent hydrophilic coating treatment, although improving its dispersibility in the water-based system, forms a physical coating type hydrophilic layer at the interface, lacks strong chemical bonding, and the binding force between the coating molecules decreases, which reduces the wear resistance of the coating. At the same time, the interfacial tension between the hydrophobic core used in this method and the hydrophilic resin system is large, resulting in poor interface compatibility and easy formation of defective voids, which affects the density of the coating, resulting in the wear resistance and other properties of the coating needing to be further improved, and the pores in the coating will affect the density of the coating after high-temperature carbonization, resulting in an increase in the carbonization height, so that the flame retardancy of the coating needs to be further improved.

[0005] In view of the technical defects in this aspect, a solution is now proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide an aerogel water-based thermal insulation coating and a preparation method thereof, so as to solve the technical problem in the prior art that the thermal insulation performance and wear resistance of water-based coatings need to be further improved.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] An aerogel water-based thermal insulation coating comprises the following raw materials in parts by weight: 70-80 parts of modified polyurethane, 10-12 parts of hydrophilic aerogel, 8-10 parts of modified chain extender, and 27-36 parts of auxiliary materials;

[0009] Furthermore, the auxiliary materials include the following raw materials in parts by weight: 16-20 parts of dispersant, 3-5 parts of stabilizer, 3-5 parts of leveling agent and 5-6 parts of anti-sticking agent, wherein the dispersant is one or both of polyvinyl alcohol and deionized water; the stabilizer is one or both of polyoxyethylene ether and fatty alcohol polyoxyethylene ether; the leveling agent is one or both of polydimethylsiloxane and polymethylsiloxane; and the anti-sticking agent is one or both of polyethylene glycol and polypropylene glycol.

[0010] The preparation method of the modified polyurethane is as follows: polytetrahydrofuran, N,N-dimethylformamide and dibutyltin dilaurate are added into a reactor and stirred; after the temperature of the reactor is increased to 50-60°C, a calculated amount of p-phenylene diisocyanate is added dropwise into the reactor; the reaction is carried out by heat preservation for 2-3 hours; and the modified polyurethane is obtained by post-processing.

[0011] The reaction equation for preparing modified polyurethane is:

[0012]

[0013] Where: .

[0014] The reaction principle for preparing modified polyurethane is as follows: under the promotion of catalyst and heating conditions, the hydroxyl groups of polytetrahydrofuran and the isocyanate groups of p-phenylene diisocyanate undergo condensation reaction, and by controlling the amount of reactants, a polyurethane prepolymer structure terminated with isocyanate groups is obtained. After further introduction of water, the residual isocyanate groups undergo addition reaction with water molecules. After the intermediate carbamic acid intermediate is decarbonated, a polyurethane chain with a primary amine terminal group is generated, and finally the modified polyurethane is prepared.

[0015] Furthermore, in the process of preparing the modified polyurethane, the usage ratio of polytetrahydrofuran, N,N-dimethylformamide and dibutyltin dilaurate is 6-8g:40-50mL:1-2g, wherein the usage amount of p-phenylene diisocyanate is 0.55-0.60 times the molar amount of hydroxyl groups in the reaction system. The post-treatment includes: after the reaction is completed, adding 0.3 times the volume of deionized water of the reaction solution to the reactor, stirring at this temperature for 30-40 minutes, transferring the reaction system to a rotary evaporator at a temperature of 80-100°C, and distilling under reduced pressure until no liquid is extracted to obtain the modified polyurethane.

[0016] Furthermore, the preparation method of the modified chain extender is as follows: glycidyl ether and N,N-dimethylformamide are added to a reactor and stirred. After nitrogen protection is introduced, the temperature of the reactor is raised to 70-80°C and a calculated amount of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine is added to the reactor, the mixture is stirred at this temperature for 40-60 minutes, and the modified chain extender is obtained by post-processing.

[0017] The reaction equation for preparing the modified chain extender is:

[0018]

[0019] Where: ; .

[0020] The reaction principle for preparing the modified chain extender is as follows: under heating conditions, the epoxy groups in the glycidyl ether undergo a ring-opening addition reaction with the active amino groups in the N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine molecule to form a new CN bond and a β-hydroxy structure. By further controlling the amount of reactants, an epoxy-terminated, oligomeric alcohol-hydrophilic modified chain extender is obtained.

[0021] Furthermore, in the process of preparing the modified chain extender, the amount ratio of glycidyl ether and N,N-dimethylformamide is 2-3g:12-15mL, wherein the amount of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine is 0.2-0.3 times the molar amount of epoxy groups in the reaction system, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is transferred to a rotary evaporator at a temperature of 80-100°C, and the pressure is reduced and evaporated until no liquid is recovered to obtain a modified chain extender.

[0022] Furthermore, the preparation method of the hydrophilic aerogel comprises the following steps:

[0023] B1. Add composite glass fiber powder, hexadecyltrimethylammonium bromide and deionized water into an autoclave. After the temperature of the autoclave is raised to 40-60°C and the pH of the reaction system is adjusted to 4-5 using acetic acid, methyl orthosilicate and tetrabutyl titanate are added into the autoclave. After stirring at this temperature for 20-30 minutes, the autoclave is sealed and heated to 160-180°C. After holding the temperature for 20-24 hours, the modified aerogel is obtained by post-processing.

[0024] The reaction principle for preparing modified aerogel is as follows: by utilizing the triethoxysilyl groups contained on the surface of composite glass fiber powder, methyl orthosilicate and tetrabutyl titanate are introduced in an acidic medium. Through the hydrolysis and condensation process, Si-O-Si and Ti-O-Ti structures are formed in situ on the fiber surface, accompanied by a small amount of heterogeneous cross-linking, such as Si-O-Ti generation, thereby constructing a three-dimensional porous inorganic skeleton, so that the inorganic phase and the fiber interface are firmly bonded, thereby preparing the modified aerogel.

[0025] B2. Add the modified aerogel, sodium hydroxide aqueous solution and N,N-dimethylformamide into the reactor, raise the temperature of the reactor to 40-60°C, keep stirring for 40-50 minutes, then add ethanolamine into the reactor, continue to keep stirring for 2-3 hours, and post-treat to obtain the hydrophilic aerogel.

[0026] The reaction principle for preparing hydrophilic aerogel is: under alkaline conditions, ethanolamine undergoes a nucleophilic addition reaction with the residual silanol groups on the surface of the aerogel, introducing hydrophilic groups such as amino and hydroxyl groups, thereby significantly improving the hydrophilicity of the material surface without destroying the original structure of the aerogel, and finally preparing a hydrophilic aerogel.

[0027] Furthermore, in step B1, the amount ratio of composite glass fiber powder, hexadecyltrimethylammonium bromide, deionized water, methyl orthosilicate and tetrabutyl titanate is 5-6 g: 0.3-0.5 g: 80-100 mL: 20-24 g: 2-3 g, and the post-processing includes: transferring the material to a drying oven at a temperature of 60° C., drying at room temperature and pressure to constant weight, and grinding through a 150-180 mesh sieve to obtain a modified aerogel;

[0028] Furthermore, in step B2, the modified aerogel, sodium hydroxide aqueous solution, N,N-dimethylformamide and ethanolamine are used in a ratio of 5-6 g: 20-30 mL: 20-30 mL: 10-12 mL, wherein the concentration of the sodium hydroxide aqueous solution is 1-2 mol / L, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and after washing with anhydrous ethanol and deionized water 3-5 times, the filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain a hydrophilic aerogel.

[0029] Furthermore, the preparation method of the composite glass fiber powder comprises the following steps:

[0030] C1. Add pre-treated glass fiber powder, ethanolamine, deionized water and N,N-dimethylformamide into a reactor. After the temperature of the reactor is raised to 40-60°C, acetic acid is used to adjust the pH of the reaction system to 4-5. The reaction mixture is stirred at this temperature for 1-2 hours, and then post-treated to obtain modified glass fiber powder.

[0031] The reaction principle for preparing modified glass fiber powder is as follows: ethanolamine is introduced into a mixed solvent and reacts with the hydroxyl groups on the surface of the pre-treated glass fiber powder under acidic conditions. The hydroxyl groups in the ethanolamine molecules undergo condensation reaction with the silanol groups on the surface of the activated glass fiber powder to form Si-OC bonds. The amino groups in the ethanolamine molecules are activated, thereby successfully introducing amino functional groups on the surface of the glass fiber powder to obtain modified glass fiber powder.

[0032] C2. Add modified glass fiber powder, anhydrous ethanol and triethylamine into a reactor. After the temperature of the reactor is increased to 40-60° C., add 5,6-epoxyhexyltriethoxysilane into the reactor. Keep warm and stir for 1-2 hours, and perform post-treatment to obtain composite glass fiber powder.

[0033] The reaction principle for preparing composite glass fiber powder is as follows: in anhydrous ethanol solution, triethylamine is used to adjust the alkaline conditions, and the epoxy groups on the 5,6-epoxyhexyltriethoxysilane molecule undergo a nucleophilic ring-opening addition reaction with the amine groups introduced on the fiber surface to form a β-hydroxyamine bond, thereby stably grafting the triethoxysilyl group structure onto the fiber surface, thereby preparing composite glass fiber powder.

[0034] Furthermore, the pretreatment step is: adding glass fiber powder and 1-2 mol / L sodium hydroxide aqueous solution to a reactor, raising the temperature of the reactor to 60-80°C, keeping warm and stirring for 30-40 minutes, and post-treating to obtain pre-treated glass fiber powder, wherein the amount ratio of glass fiber powder to 1-2 mol / L sodium hydroxide aqueous solution is 1g:10-12mL, and the post-treatment includes: after the reaction is completed, lowering the temperature of the reactor to room temperature, filtering the reaction liquid to collect the filter cake, and washing it with anhydrous ethanol and deionized water for 3-5 times, transferring the filter cake to a drying oven at a temperature of 80°C, and vacuum drying it to constant weight to obtain the pre-treated glass fiber powder.

[0035] The principle of preparing pre-treated glass fiber powder is: by treating the glass fiber powder in an alkaline sodium hydroxide solution, under heating conditions, the surface impurities are stripped off, and the Si-O-Si bonds are partially broken, causing more active hydroxyl groups to be exposed, providing reaction sites for subsequent reactions, and obtaining pre-treated glass fiber powder.

[0036] Furthermore, in step C1, the ratio of the amount of pre-treatment glass fiber powder, ethanolamine, deionized water and N,N-dimethylformamide is 7-8 g: 8-10 g: 30-36 mL: 20-24 mL, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and after washing with anhydrous ethanol and deionized water 3-5 times, the filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain modified glass fiber powder;

[0037] Furthermore, in step C2, the amount ratio of the modified glass fiber powder, anhydrous ethanol, triethylamine and 5,6-epoxyhexyltriethoxysilane is 6-7g:30-36mL:0.3-0.5g:1-2g, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and after washing it with anhydrous ethanol 3-5 times, the filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain a composite glass fiber powder.

[0038] The present invention also discloses a method for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0039] S1. Weigh 70-80 parts of modified polyurethane, 10-12 parts of hydrophilic aerogel, and 300-400 parts of N,N-dimethylformamide in parts by weight and add them to a reactor. After nitrogen protection, raise the temperature of the reactor to 70-80°C and add 8-10 parts of modified chain extender to the reactor. Keep the mixture warm and stir for 1-2 hours, and perform post-treatment to obtain a composite polyurethane.

[0040] The reaction principle for preparing composite polyurethane is as follows: the modified chain extender acts as a bridging agent and cross-linking agent to connect the modified polyurethane main chain and the hydrophilic aerogel particles dispersed in the system. Through the ring-opening condensation reaction between amine and epoxy, a three-dimensional network structure with polyurethane as the main body, aerogel as the inorganic reinforcing phase, and epoxy chain extender as the cross-linking node is constructed, thereby obtaining composite polyurethane.

[0041] S2. Weigh 88-102 parts of composite polyurethane, 16-20 parts of dispersant, 3-5 parts of stabilizer, 3-5 parts of leveling agent and 5-6 parts of anti-sticking agent in parts by weight, add them into a stirring kettle, stir at room temperature for 10-15 minutes, pass through a 100-120 mesh sieve, and store in the dark to obtain a water-based thermal insulation coating.

[0042] Furthermore, in step S1, post-processing includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is transferred to a rotary evaporator at a temperature of 80-100°C, and the pressure is reduced and evaporated until no liquid is extracted to obtain a composite polyurethane.

[0043] The present invention has the following beneficial effects:

[0044] 1. The hydrophilic aerogel structure introduced into the water-washable thermal insulation coating of the present invention has a high porosity and a three-dimensional continuous skeleton structure. The interior is filled with a large amount of still air, which effectively inhibits heat conduction and convection. Its pores can also significantly reduce the transmission of infrared radiation, forming an overall high-efficiency thermal resistance barrier with three barriers to heat conduction, convection and radiation. At the same time, in the system, the hydrophilic aerogel is evenly dispersed in the coating matrix and constructs a stable composite network structure with the organic phase, so that heat is scattered and blocked multiple times on a microscopic scale, thereby reducing the overall heat flux density of the coating. Moreover, this structure does not introduce too many thermal bridge channels while ensuring the density of the paint film, thus avoiding heat leakage and further improving the thermal insulation effect. Ultimately, through the structural advantages of the aerogel and the orderly distribution of the composite system, effective interference with the heat migration path is achieved, thereby significantly improving the thermal insulation performance of the water-based thermal insulation coating.

[0045] 2. The porous structure of the hydrophilic aerogel prepared by the present invention can effectively reduce thermal conductivity while delaying the propagation path of heat and flames. Combined with the phosphate and triazine structures introduced in the modified cross-linking agent, a synergistic flame retardant system is formed, which gives the coating a good flame retardant effect. At the same time, the inorganic components introduced into the coating, such as Si-O-Si and Ti-O-Ti skeleton structures, have good absorption and scattering effects on ultraviolet rays, further improving the anti-ultraviolet aging performance of the paint film. In addition, the synergistic interface construction between the composite glass fiber powder and the aerogel through modified cross-linking not only stabilizes the three-dimensional microstructure, but also increases the cross-linking density of the material and enhances the structural stability, thereby enhancing the stability of the inorganic phase in the photothermal environment, thereby improving the overall durability and environmental adaptability of the coating. Finally, through the high integration of multiple functions at the structural level, the coating exhibits excellent comprehensive protective performance in complex application scenarios.

[0046] 3. The composite glass fiber powder prepared by the present invention serves as the skeleton support material of the hydrophilic aerogel in the system, which not only improves the mechanical strength of the coating, but also forms a strong chemical bond with the hydrophilic aerogel under the action of its surface hydroxyl and amino modifications, significantly improving the interfacial adhesion. At the same time, the hydrophilic aerogel particles are dispersed in the polyurethane network through the modified chain extender, participating in the construction of the three-dimensional structure. At the same time, the porous structure locally buffers the impact of external forces, inhibits the expansion of microcracks, and plays a dual role of energy absorption and wear resistance. The coating is cross-linked through the participation of inorganic components to form a dense and uniform microscopic layer with high hardness and scratch resistance. Finally, through the coordinated distribution of the organic flexible phase and the inorganic rigid phase, while ensuring the integrity of the overall coating, its structural stability during the friction and wear process is enhanced, thereby giving the material excellent wear resistance. DETAILED DESCRIPTION

[0047] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] In the present invention, glass fiber powder was purchased from Shanghai MacLean Biochemical Technology Co., Ltd. with the product number F792079;

[0049] In the present invention, polytetrahydrofuran was purchased from Shanghai MacLean Biochemical Technology Co., Ltd. with the product number P902444;

[0050] In the present invention, polyoxyethylene ether was purchased from Shanghai MacLean Biochemical Technology Co., Ltd. with the product number P799401;

[0051] In the present invention, polymethylsiloxane was purchased from Shanghai Yuanye Biotechnology Co., Ltd. with the product number S51664;

[0052] In the present invention, polyethylene glycol was purchased from Shanghai Yuanye Biotechnology Co., Ltd. with the product number V32174.

[0053] Example 1

[0054] This embodiment provides a method for preparing a hydrophilic aerogel for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0055] Step 1: Preparation of pre-treated glass fiber powder

[0056] Weigh: 100.0 g of glass fiber powder and 1000.0 mL of 1 mol / L sodium hydroxide aqueous solution were added to the reactor, the reactor temperature was raised to 60°C, and the mixture was stirred for 30 minutes. After the reaction was completed, the reactor temperature was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed three times with anhydrous ethanol and deionized water. The filter cake was transferred to a drying oven at 80°C and vacuum dried to constant weight to obtain pretreated glass fiber powder.

[0057] Step 2: Preparation of modified glass fiber powder

[0058] Weigh: 70.0g pre-treated glass fiber powder, 80.0g ethanolamine, 300.0mL deionized water and 200.0mL N,N-dimethylformamide and add them to the reactor. After the temperature of the reactor is raised to 40°C, acetic acid is used to adjust the pH of the reaction system to 4, and the mixture is stirred for 1h. After the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed three times with anhydrous ethanol and deionized water. The filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain modified glass fiber powder.

[0059] Step 3: Preparation of composite glass fiber powder

[0060] Weigh: 60.0 g of modified glass fiber powder, 300.0 mL of anhydrous ethanol and 3.0 g of triethylamine were added to the reactor. After the temperature of the reactor was raised to 40°C, 10.0 g of 5,6-epoxyhexyltriethoxysilane was added to the reactor and stirred for 1 hour. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and after washing it with anhydrous ethanol three times, the filter cake was transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain a composite glass fiber powder.

[0061] Step ④: Preparation of modified aerogel

[0062] Weigh: 50.0g composite glass fiber powder, 3.0g hexadecyltrimethylammonium bromide and 800.0mL deionized water were added to a high-pressure reactor. The reactor temperature was raised to 40°C and acetic acid was used to adjust the pH of the reaction system to 4. Then, 200.0g methyl orthosilicate and 20.0g tetrabutyl titanate were added to the reactor. After stirring for 20 minutes, the high-pressure reactor was sealed and heated to 160°C. After keeping warm for 20 hours, the material was transferred to a drying oven at 60°C, dried at room temperature and pressure to constant weight, and then ground through a 150-mesh sieve to obtain a modified aerogel.

[0063] Step 5: Preparation of hydrophilic aerogel

[0064] Weigh: 50.0 g modified aerogel, 200.0 mL 1 mol / L sodium hydroxide aqueous solution and 200.0 mL N, N-dimethylformamide were added to the reactor, the reactor temperature was raised to 40 ° C, and after stirring for 40 minutes, 100.0 mL ethanolamine was added to the reactor, and the stirring was continued for 2 hours. After the reaction was completed, the reactor temperature was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and it was washed three times with anhydrous ethanol and deionized water. The filter cake was transferred to a drying oven at a temperature of 80 ° C and vacuum dried to constant weight to obtain a hydrophilic aerogel.

[0065] Example 2

[0066] This embodiment provides a method for preparing a hydrophilic aerogel for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0067] Step 1: Preparation of pre-treated glass fiber powder

[0068] Weigh: 100.0 g of glass fiber powder and 1200.0 mL of 2 mol / L sodium hydroxide aqueous solution were added to the reactor, the reactor temperature was raised to 80°C, and the mixture was stirred for 40 minutes. After the reaction was completed, the reactor temperature was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed 5 times with anhydrous ethanol and deionized water. The filter cake was transferred to a drying oven at 80°C and vacuum dried to constant weight to obtain pretreated glass fiber powder.

[0069] Step 2: Preparation of modified glass fiber powder

[0070] Weigh: 80.0g pre-treated glass fiber powder, 100.0g ethanolamine, 360.0mL deionized water and 240.0mL N,N-dimethylformamide and add them to the reactor. After the temperature of the reactor is raised to 60°C, acetic acid is used to adjust the pH of the reaction system to 5, and the mixture is stirred for 2h. After the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 5 times with anhydrous ethanol and deionized water. The filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain modified glass fiber powder.

[0071] Step 3: Preparation of composite glass fiber powder

[0072] Weigh: 70.0 g of modified glass fiber powder, 360.0 mL of anhydrous ethanol and 5.0 g of triethylamine are added to the reactor. After the temperature of the reactor is raised to 60°C, 20.0 g of 5,6-epoxyhexyltriethoxysilane is added to the reactor and stirred for 2 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and after washing with anhydrous ethanol 5 times, the filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain a composite glass fiber powder.

[0073] Step ④: Preparation of modified aerogel

[0074] Weigh: 60.0g composite glass fiber powder, 5.0g hexadecyltrimethylammonium bromide and 1000.0mL deionized water were added to a high-pressure reactor. The reactor temperature was raised to 60°C and acetic acid was used to adjust the pH of the reaction system to 4. Then, 240.0g methyl orthosilicate and 30.0g tetrabutyl titanate were added to the reactor. After stirring for 30 minutes, the high-pressure reactor was sealed and heated to 180°C. After keeping warm for 24 hours, the material was transferred to a drying oven at 60°C, dried at room temperature and pressure to constant weight, and then ground through a 180-mesh sieve to obtain a modified aerogel.

[0075] Step 5: Preparation of hydrophilic aerogel

[0076] Weigh: 60.0g modified aerogel, 300.0mL2mo / L sodium hydroxide aqueous solution and 300.0mLN,N-dimethylformamide were added to the reactor, the temperature of the reactor was raised to 60℃, and after stirring for 50min, 120.0mL ethanolamine was added to the reactor, and stirring was continued for 3h. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and it was washed with anhydrous ethanol and deionized water 5 times. The filter cake was transferred to a drying oven at a temperature of 80℃ and vacuum dried to constant weight to obtain a hydrophilic aerogel.

[0077] Example 3

[0078] This embodiment provides a method for preparing a hydrophilic aerogel for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0079] Step 1: Preparation of pre-treated glass fiber powder

[0080] Weigh: 100.0 g of glass fiber powder and 1000.0 mL of 2 mol / L sodium hydroxide aqueous solution were added to the reactor, the reactor temperature was raised to 70°C, and the mixture was stirred for 36 minutes. After the reaction was completed, the reactor temperature was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed 4 times with anhydrous ethanol and deionized water. The filter cake was transferred to a drying oven at 80°C and vacuum dried to constant weight to obtain pretreated glass fiber powder.

[0081] Step 2: Preparation of modified glass fiber powder

[0082] Weigh: 72.0g pre-treated glass fiber powder, 96.0g ethanolamine, 320.0mL deionized water and 210.0mL N,N-dimethylformamide and add them to the reactor. After the reactor temperature is raised to 50°C, acetic acid is used to adjust the pH of the reaction system to 4, and the mixture is stirred for 2h. After the reaction is completed, the reactor temperature is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 4 times with anhydrous ethanol and deionized water. The filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain modified glass fiber powder.

[0083] Step 3: Preparation of composite glass fiber powder

[0084] Weigh: 64.0g modified glass fiber powder, 320.0mL anhydrous ethanol and 4.0g triethylamine are added to the reactor. After the temperature of the reactor is raised to 50°C, 16.0g 5,6-epoxyhexyltriethoxysilane is added to the reactor and stirred for 2 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and after washing with anhydrous ethanol 4 times, the filter cake is transferred to a drying oven at a temperature of 80°C and vacuum dried to constant weight to obtain a composite glass fiber powder.

[0085] Step ④: Preparation of modified aerogel

[0086] Weigh: 54.0g composite glass fiber powder, 4.0g hexadecyltrimethylammonium bromide and 960.0mL deionized water were added to a high-pressure reactor. The reactor temperature was raised to 50°C and acetic acid was used to adjust the pH of the reaction system to 4. Then, 210.0g methyl orthosilicate and 25.0g tetrabutyl titanate were added to the reactor. After stirring for 24 minutes, the high-pressure reactor was sealed and heated to 172°C. After keeping warm for 21 hours, the material was transferred to a drying oven at 60°C, dried at room temperature and pressure to constant weight, and then ground through a 160-mesh sieve to obtain a modified aerogel.

[0087] Step 5: Preparation of hydrophilic aerogel

[0088] Weigh: 54.0g modified aerogel, 250.0mL2mo / L sodium hydroxide aqueous solution and 250.0mLN,N-dimethylformamide were added to the reactor, the temperature of the reactor was raised to 50℃, and after stirring for 45min, 120.0mL ethanolamine was added to the reactor, and stirring was continued for 3h. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and it was washed 4 times with anhydrous ethanol and deionized water. The filter cake was transferred to a drying oven at a temperature of 80℃ and vacuum dried to constant weight to obtain a hydrophilic aerogel.

[0089] Example 4

[0090] This embodiment provides a method for preparing a modified chain extender for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0091] Weigh: 20.0g of glycidyl ether and 120.0mL of N,N-dimethylformamide were added to the reactor and stirred. After nitrogen protection was introduced, the temperature of the reactor was raised to 70°C and 0.2 times the molar amount of epoxy groups in the reaction system of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine was added to the reactor. The mixture was stirred for 40 minutes at this temperature. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction solution was transferred to a rotary evaporator at a temperature of 80°C. The pressure was reduced and evaporated until no liquid was recovered to obtain a modified chain extender.

[0092] Example 5

[0093] This embodiment provides a method for preparing a modified chain extender for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0094] Weigh: 30.0g of glycidyl ether and 150.0mL of N,N-dimethylformamide were added to the reactor and stirred. After nitrogen protection was introduced, the temperature of the reactor was raised to 80°C and 0.3 times the molar amount of epoxy groups in the reaction system of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine was added to the reactor. The mixture was stirred for 60 minutes at this temperature. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction solution was transferred to a rotary evaporator at a temperature of 100°C. The pressure was reduced and evaporated until no liquid was recovered to obtain a modified chain extender.

[0095] Example 6

[0096] This embodiment provides a method for preparing a modified chain extender for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0097] Weigh: 25.0g of glycidyl ether and 135.0mL of N,N-dimethylformamide were added to the reactor and stirred. After nitrogen protection was introduced, the temperature of the reactor was raised to 72°C and 0.2 times the molar amount of epoxy groups in the reaction system of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine was added to the reactor. The mixture was stirred for 50 minutes at this temperature. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction solution was transferred to a rotary evaporator at a temperature of 90°C. The pressure was reduced and evaporated until no liquid was recovered to obtain a modified chain extender.

[0098] Example 7

[0099] This embodiment provides a method for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0100] Step 1: Preparation of modified polyurethane

[0101] Weigh: 60.0g of polytetrahydrofuran, 400.0mL of N,N-dimethylformamide and 10.0g of dibutyltin dilaurate are added to the reactor and stirred. After the temperature of the reactor is raised to 50°C, 0.55 times the molar amount of hydroxyl group in the reaction system of p-phenylene diisocyanate is added dropwise to the reactor. The reaction is kept warm for 2h. After the reaction is completed, 0.3 times the volume of the reaction solution of deionized water is added to the reactor. After keeping warm and stirring for 30min, the reaction system is transferred to a rotary evaporator at a temperature of 80°C and distilled under reduced pressure until no liquid is produced to obtain a modified polyurethane.

[0102] Step 2: Preparation of composite polyurethane

[0103] 70 parts of modified polyurethane, 10 parts of the hydrophilic aerogel prepared in Example 1 and 300 parts of N,N-dimethylformamide were weighed and added to a reactor. After nitrogen protection was introduced, the temperature of the reactor was raised to 70° C. and 8 parts of the modified chain extender prepared in Example 4 were added to the reactor. The mixture was stirred at this temperature for 1 hour. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction solution was transferred to a rotary evaporator at 80° C. and evaporated under reduced pressure until no liquid was recovered to obtain a composite polyurethane.

[0104] Step 3: Preparation of water-based thermal insulation coating

[0105] 88 parts of composite polyurethane, 16 parts of deionized water, 3 parts of polyoxyethylene ether, 3 parts of polymethylsiloxane and 5 parts of polyethylene glycol were weighed and added into a stirring kettle. After stirring at room temperature for 10 minutes, the mixture was passed through a 100-mesh sieve and stored away from light to obtain a water-based thermal insulation coating.

[0106] Example 8

[0107] This embodiment provides a method for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0108] Step 1: Preparation of modified polyurethane

[0109] Weigh: 80.0g of polytetrahydrofuran, 500.0mL of N,N-dimethylformamide and 20.0g of dibutyltin dilaurate are added to a reactor and stirred. After the temperature of the reactor is raised to 60°C, 0.60 times the molar amount of hydroxyl group in the reaction system of p-phenylene diisocyanate is added dropwise to the reactor. The reaction is kept warm for 3 hours. After the reaction is completed, 0.3 times the volume of the reaction solution is added to the reactor. After stirring for 40 minutes, the reaction system is transferred to a rotary evaporator at a temperature of 100°C and distilled under reduced pressure until no liquid is produced to obtain a modified polyurethane.

[0110] Step 2: Preparation of composite polyurethane

[0111] 80 parts of modified polyurethane, 12 parts of the hydrophilic aerogel prepared in Example 2, and 400 parts of N,N-dimethylformamide were weighed and added to a reactor. After nitrogen protection was introduced, the temperature of the reactor was raised to 80° C., and 10 parts of the modified chain extender prepared in Example 5 were added to the reactor. The mixture was stirred for 2 hours at this temperature. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction solution was transferred to a rotary evaporator at a temperature of 100° C. and evaporated under reduced pressure until no liquid was recovered to obtain a composite polyurethane.

[0112] Step 3: Preparation of water-based thermal insulation coating

[0113] 102 parts of composite polyurethane, 20 parts of deionized water, 5 parts of polyoxyethylene ether, 5 parts of polymethylsiloxane and 6 parts of polyethylene glycol were weighed and added into a stirring kettle. After stirring at room temperature for 15 minutes, the mixture was passed through a 120-mesh sieve and stored away from light to obtain a water-based thermal insulation coating.

[0114] Example 9

[0115] This embodiment provides a method for preparing an aerogel water-based thermal insulation coating, comprising the following steps:

[0116] Step 1: Preparation of modified polyurethane

[0117] Weigh: 70.0g of polytetrahydrofuran, 450.0mL of N,N-dimethylformamide and 16.0g of dibutyltin dilaurate are added to the reactor and stirred. After the temperature of the reactor is raised to 54°C, 0.58 times the molar amount of hydroxyl group in the reaction system of p-phenylene diisocyanate is added dropwise to the reactor. The reaction is kept warm for 3h. After the reaction is completed, 0.3 times the volume of the reaction solution of deionized water is added to the reactor. After stirring for 35min, the reaction system is transferred to a rotary evaporator at a temperature of 90°C and distilled under reduced pressure until no liquid is produced to obtain a modified polyurethane.

[0118] Step 2: Preparation of composite polyurethane

[0119] 72 parts of modified polyurethane, 12 parts of the hydrophilic aerogel prepared in Example 3 and 360 parts of N,N-dimethylformamide were weighed and added to a reactor. After nitrogen protection was introduced, the temperature of the reactor was raised to 75°C and 10 parts of the modified chain extender prepared in Example 6 were added to the reactor. The mixture was stirred for 2 hours at this temperature. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction solution was transferred to a rotary evaporator at a temperature of 90°C and evaporated under reduced pressure until no liquid was recovered to obtain a composite polyurethane.

[0120] Step 3: Preparation of water-based thermal insulation coating

[0121] 94 parts of composite polyurethane, 18 parts of deionized water, 4 parts of polyoxyethylene ether, 4 parts of polymethylsiloxane and 5.5 parts of polyethylene glycol were weighed and added into a stirring kettle. After stirring at room temperature for 12 minutes, the mixture was passed through a 120-mesh sieve and stored away from light to obtain a water-based thermal insulation coating.

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 9 is that the modified chain extender is omitted in step 2.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 9 is that, in the preparation process of the hydrophilic aerogel used in step 2, step ② is omitted, and in step ③, an equal amount of pre-treated glass fiber powder is used instead of the modified glass fiber powder.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 9 is that step ⑤ is omitted during the preparation of the hydrophilic aerogel used in step 2, and an equal amount of the modified aerogel prepared in step ④ is used to replace the hydrophilic aerogel.

[0128] Performance testing:

[0129] The flame retardant properties of the cured paint surfaces of the water-based thermal insulation coatings prepared in Examples 7-9 and Comparative Examples 1-3 were measured with reference to the standard GB 28374-2012 "Cable Fire Retardant Coatings";

[0130] The thermal conductivity of the paint surface of the water-based thermal insulation coatings prepared in Examples 7-9 and Comparative Examples 1-3 after curing was measured with reference to the standard GB / T 10297-2015 "Determination of thermal conductivity of non-metallic solid materials - Hot wire method";

[0131] The mass loss of the paint surface after curing of the water-based thermal insulation coatings prepared in Examples 7-9 and Comparative Examples 1-3 was measured with reference to the standard YY / T 0988.15-2016 "Surgical Implant Coatings Part 15: Test Method for Wear Resistance of Metal Thermal Spray Coatings".

[0132] With reference to the standard GB / T 23987-2009 "Artificial weathering exposure of paint and varnish coatings, exposure to fluorescent ultraviolet light and water", the water-based thermal insulation coatings prepared in Examples 7-9 and Comparative Examples 1-3 were subjected to ultraviolet aging treatment after curing, and the mass loss change rate of the coating was measured with reference to the standard YY / T 0988.15-2016; the specific data are shown in Table 1.

[0133] Table 1 - Performance test data of each sample

[0134]

[0135] Data Analysis:

[0136] After comparing and analyzing the data in Table 1, it can be found that the carbonization height of the paint surface after curing of the water-based thermal insulation coating prepared by the present invention is 0.7m, and the thermal conductivity is 0.046W·(m·K). -1 , the mass loss is 3.8 mg, and the mass loss change rate after ultraviolet aging is 100.8%. All data are better than the control example.

[0137] In Comparative Example 1, after the modified chain extender with a phosphorus-nitrogen structure was removed, the polyurethane main chain lacked the necessary cross-linking and heat-stabilizing groups, resulting in a weak coating molecular chain and a loose structure. Chain scission and peeling easily occurred under mechanical stress and thermal field, significantly weakening the overall mechanical properties of the material. At the same time, the phosphorus and nitrogen elements in the chain extender simultaneously imparted carbon formation promotion and free radical inhibition functions. After their absence, the flame retardancy decreased significantly, and the continuity of the carbon layer was poor. In addition, the lack of polar groups led to poor surface wettability, weakened interfacial hydrophilic synergy, and reduced cross-linking density and structural stability, which would lead to easy photodegradation and bond breaking reactions after exposure to ultraviolet light, resulting in increased structural damage and severe wear after aging.

[0138] Comparative Example 2 uses pre-treated glass fiber powder to directly prepare composite glass fiber powder, resulting in the effective formation of a stable interface between the fiber structure and the aerogel, and the structural dispersion and bonding strength are greatly reduced. In the composite system, this uncross-linked glass fiber cannot be embedded in the construction of a three-dimensional network skeleton, and is prone to slippage or interface peeling when stress is loaded, resulting in a decrease in the overall wear resistance of the material. At the same time, the incompleteness of the skeleton also destroys the continuous heat conduction and heat shielding channels, resulting in weakened thermal stability. The lack of polar functional groups on the surface of the glass fiber also weakens the hydrophilic synergy between it and the hydrophilic aerogel. In addition, during the UV aging process, the weak interface between the glass fiber and the surrounding matrix is ​​more likely to become a stress concentration area, promoting structural cracking and fragmentation, and worsening wear.

[0139] In Comparative Example 3, an equal amount of modified aerogel was used to replace the hydrophilic aerogel. The aerogel material without surface modification was difficult to disperse evenly in the system, and its interfacial bonding force with polyurethane was weak, making it difficult to play its due microporous thermal insulation and structural support role. The discontinuity of the aerogel network resulted in a decrease in the overall density and mechanical stability of the coating, and structural damage and shedding were prone to occur after friction or aging. At the same time, the aerogel lacking polar modification on the surface could not participate in the interfacial wetting synergy, which significantly reduced the hydrophilicity of the material surface and led to a decrease in UV resistance. After UV aging, the interface was prone to loosening or microcracks expanded, exacerbating the degradation and wear of the surface structure.

[0140] Finally, it is explained that the present invention constructs a multifunctional polyurethane composite coating by introducing a phosphorus-nitrogen cross-linked modified chain extender, a hydrophilic aerogel and a modified polyurethane. The three form a synergistic effect of structure-interface-performance in the system: the modified chain extender improves the cross-linking density and carbon-forming ability of the polyurethane matrix, and enhances the mechanical and flame retardant properties; the hydrophilic aerogel constructs a stable and continuous porous skeleton, improves thermal insulation, and the internal composite glass fiber powder forms a three-dimensional support structure, which significantly improves wear resistance and structural stability; the modified polyurethane forms target functional group end-capping through chain segment optimization, which improves the dispersion performance of the hydrophilic aerogel. Finally, through the cooperation of the three functional components, the complementary soft-rigid structure, and the tight interface bonding, the coating exhibits excellent composite performance in UV aging, friction and wear, and hydrophilic thermal insulation.

[0141] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0142] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0143] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An aerogel water-based thermal insulation coating, characterized in that: The invention comprises the following raw materials in parts by weight: 70-80 parts of modified polyurethane, 10-12 parts of hydrophilic aerogel, 8-10 parts of modified chain extender and 27-36 parts of auxiliary materials; The preparation method of the modified polyurethane is as follows: polytetrahydrofuran, N,N-dimethylformamide and dibutyltin dilaurate are added into a reactor and stirred; after the temperature of the reactor is increased to 50-60°C, a calculated amount of p-phenylene diisocyanate is added dropwise into the reactor; the reaction is carried out by heat preservation for 2-3 hours; and the modified polyurethane is obtained by post-processing.

2. The aerogel water-based thermal insulation coating according to claim 1, characterized in that: The auxiliary materials include the following raw materials in parts by weight: 16-20 parts of a dispersant, 3-5 parts of a stabilizer, 3-5 parts of a leveling agent, and 5-6 parts of an anti-sticking agent. In the process of preparing the modified polyurethane, the usage ratio of the polytetrahydrofuran, N,N-dimethylformamide, and dibutyltin dilaurate is 6-8 g:40-50 mL:1-2 g, wherein the usage amount of p-phenylene diisocyanate is 0.55-0.60 times the molar amount of hydroxyl groups in the reaction system.

3. The aerogel water-based thermal insulation coating according to claim 1, characterized in that: The preparation method of the modified chain extender comprises the following steps: adding glycidyl ether and N,N-dimethylformamide into a reactor and stirring; introducing nitrogen for protection; raising the temperature of the reactor to 70-80° C.; adding a calculated amount of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine into the reactor; maintaining the temperature and stirring for 40-60 minutes; and performing post-treatment to obtain the modified chain extender.

4. The aerogel water-based thermal insulation coating according to claim 3, characterized in that: In the process of preparing the modified chain extender, the usage ratio of glycidyl ether and N,N-dimethylformamide is 2-3 g:12-15 mL, wherein the usage amount of N-[(10-oxo-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)methyl]-1,3,5-triazine-2,4,6-triamine is 0.2-0.3 times the molar amount of epoxy groups in the reaction system.

5. The aerogel water-based thermal insulation coating according to claim 1, characterized in that: The preparation method of the hydrophilic aerogel comprises the following steps: B1. Add composite glass fiber powder, hexadecyltrimethylammonium bromide and deionized water into an autoclave. After the temperature of the autoclave is raised to 40-60°C and the pH of the reaction system is adjusted to 4-5 using acetic acid, methyl orthosilicate and tetrabutyl titanate are added into the autoclave. After stirring at this temperature for 20-30 minutes, the autoclave is sealed and heated to 160-180°C. After holding the temperature for 20-24 hours, the modified aerogel is obtained by post-processing. B2. Add the modified aerogel, sodium hydroxide aqueous solution and N,N-dimethylformamide into the reactor, raise the temperature of the reactor to 40-60°C, keep stirring for 40-50 minutes, then add ethanolamine into the reactor, continue to keep stirring for 2-3 hours, and post-treat to obtain the hydrophilic aerogel.

6. The aerogel water-based thermal insulation coating according to claim 5, characterized in that: In step B1, the amount ratio of the composite glass fiber powder, hexadecyltrimethylammonium bromide, deionized water, methyl orthosilicate and tetrabutyl titanate is 5-6g:0.3-0.5g:80-100mL:20-24g:2-3g; in step B2, the amount ratio of the modified aerogel, sodium hydroxide aqueous solution, N,N-dimethylformamide and ethanolamine is 5-6g:20-30mL:20-30mL:10-12mL, wherein the concentration of the sodium hydroxide aqueous solution is 1-2 mol / L.

7. The aerogel water-based thermal insulation coating according to claim 5, characterized in that: The preparation method of the composite glass fiber powder comprises the following steps: C1. Add pre-treated glass fiber powder, ethanolamine, deionized water and N,N-dimethylformamide into a reactor. After the temperature of the reactor is raised to 40-60°C, acetic acid is used to adjust the pH of the reaction system to 4-5. The reaction mixture is stirred at this temperature for 1-2 hours, and then post-treated to obtain modified glass fiber powder. C2. Add modified glass fiber powder, anhydrous ethanol and triethylamine into a reactor. After the temperature of the reactor is increased to 40-60° C., add 5,6-epoxyhexyltriethoxysilane into the reactor. Keep warm and stir for 1-2 hours, and perform post-treatment to obtain composite glass fiber powder.

8. The aerogel water-based thermal insulation coating according to claim 7, characterized in that: In step C1, the amount ratio of the pretreated glass fiber powder, ethanolamine, deionized water and N,N-dimethylformamide is 7-8 g: 8-10 g: 30-36 mL: 20-24 mL; in step C2, the amount ratio of the modified glass fiber powder, anhydrous ethanol, triethylamine and 5,6-epoxyhexyltriethoxysilane is 6-7 g: 30-36 mL: 0.3-0.5 g: 1-2 g.

9. The method for preparing an aerogel water-based thermal insulation coating according to any one of claims 1 to 8, characterized in that: The preparation method of the aerogel water-based thermal insulation coating comprises the following steps: S1. Weigh 70-80 parts of modified polyurethane, 10-12 parts of hydrophilic aerogel, and 300-400 parts of N,N-dimethylformamide in parts by weight and add them to a reactor. After nitrogen protection, raise the temperature of the reactor to 70-80°C and add 8-10 parts of modified chain extender to the reactor. Keep the mixture warm and stir for 1-2 hours, and perform post-treatment to obtain a composite polyurethane. S2. Weigh 88-102 parts of composite polyurethane, 16-20 parts of dispersant, 3-5 parts of stabilizer, 3-5 parts of leveling agent and 5-6 parts of anti-sticking agent in parts by weight, add them into a stirring kettle, stir at room temperature for 10-15 minutes, pass through a 100-120 mesh sieve, and store in the dark to obtain a water-based thermal insulation coating.

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