Inorganic water-based aerogel thermal insulation coating and preparation method thereof

Abstract

The application discloses an inorganic water-based aerogel thermal insulation coating and a preparation method thereof. The coating is composed of an inorganic binder, functional aerogel composite powder, composite functional fillers, a styrene-acrylic emulsion, a cellulose ether, an additive and water. The preparation method adopts a'step-by-step feeding and low-speed final mixing' process, part of the aerogel composite powder is dispersed with the fillers, the emulsion and the binder are added, and the remaining aerogel is finally mixed gently. Through the compounding of components and the optimization of the process, the application solves the problems that the aerogel is easy to break and difficult to disperse in the coating, and the obtained coating has extremely low thermal conductivity, A-grade fireproofing, high adhesive strength and good flexibility, and has excellent comprehensive performance, and is suitable for energy-saving and thermal insulation in the fields of building and industry.

Description

Technical Field

[0001] This invention relates to the field of building energy conservation and industrial thermal insulation materials technology, specifically to an inorganic water-based aerogel thermal insulation coating and its preparation method. Background Technology

[0002] With the increasing national requirements for building and industrial energy conservation, the demand for high-performance thermal insulation materials is growing. Traditional thermal insulation materials, such as polystyrene boards and polyurethane, suffer from problems such as flammability, easy aging, and poor durability. Traditional inorganic thermal insulation mortars, on the other hand, have disadvantages such as high thermal conductivity, poor insulation effect, and high dry density.

[0003] Aerogel is a nanoscale porous solid material formed by replacing the liquid phase in the gel with gas through the sol-gel method and a certain drying method. Examples include gelatin, gum arabic, silica gel, hair, and nails. Aerogel also has the properties of gel, namely, expansion, thixotropy, and separation. Aerogel coating is a new type of coating that uses aerogel as the main component. It has excellent heat insulation, sound insulation, and fire resistance properties, and is therefore widely used in construction, transportation, electronics and other fields. As a nanoporous material, aerogel is known as the lightest solid in the world. It has an extremely low thermal conductivity (less than 0.020 W / (m·K) at room temperature), high specific surface area and excellent fire resistance, making it an ideal heat insulation material. However, applying aerogel to the coating field faces many challenges: (1) Dispersion problem: The nano-network structure of aerogel is fragile and easily broken under stirring and shearing, causing its nanoporous structure to collapse and lose its super heat insulation performance. (2) Balance between strength and flexibility: Pure aerogel has low strength and is brittle, making it difficult to form a film directly. When it is combined with inorganic substrates, if too much inorganic substrate is used, the coating film will have poor flexibility and be prone to cracking; if too little is used, the coating film will have insufficient strength. (3) Compatibility with water-based systems: Aerogels are hydrophobic, so how to make them stably dispersed in water-based inorganic systems and ensure storage stability is a technical challenge. (4) Cost issues: Aerogel raw materials are expensive, so how to control costs while ensuring performance through optimization of formulation and process is the key to industrialization.

[0004] Therefore, developing an inorganic water-based coating that can effectively protect the aerogel structure and has excellent thermal insulation performance, fire resistance, ease of construction and durability has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an inorganic water-based aerogel thermal insulation coating. This coating has low thermal conductivity, is fireproof and non-combustible, has high bonding strength, good flexibility, is green and environmentally friendly, and has a mild preparation process that can protect the nanostructure of the aerogel to the greatest extent.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0007] An inorganic water-based aerogel thermal insulation coating is made from the following raw materials in parts by weight: 15-35 parts of functional aerogel composite powder, 10-25 parts of composite functional filler, 5-15 parts of styrene-acrylic emulsion, 20-40 parts of inorganic binder, 0.1-0.5 parts of cellulose ether, 1-3 parts of additives, and 20-35 parts of water.

[0008] The functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-pore ceramic microspheres in a mass ratio of (3~5):1.

[0009] The composite functional filler is composed of hollow glass microspheres and modified montmorillonite in a mass ratio of 2:(0.5-1), and the particle size of the hollow glass microspheres is 10-50μm.

[0010] Preferably, the modified silica aerogel powder is prepared by the following method:

[0011] a. Mix 1-5 wt% of nanocellulose aqueous dispersion with 10-20 wt% of aqueous silicone-acrylic emulsion at a mass ratio, then add 0.1-0.5 wt% of crosslinking agent and stir at low speed until homogeneous to obtain composite coating solution;

[0012] b. Wet the hydrophobic SiO2 aerogel in a small amount of ethanol to obtain a pretreated aerogel;

[0013] c. Slowly add the pretreated aerogel to the composite coating solution and stir at a low shear rate of 200-500 rpm for 30-60 minutes to obtain a mixed slurry;

[0014] d. After heating the mixed slurry at 40-45℃ for 30-40 minutes, spray dry it to obtain modified silica aerogel powder.

[0015] Preferably, in step a, the mass ratio of the nanocellulose aqueous dispersion to the aqueous silicone-acrylic emulsion is 1:(2-3.5).

[0016] Preferably, the crosslinking agent is carbodiimide.

[0017] Preferably, the solid-liquid ratio of the pretreated aerogel to the composite coating liquid in step c is 1g:(8-10)mL.

[0018] Preferably, the particle size of the nanoscale closed-pore ceramic microspheres is 50~500nm.

[0019] Preferably, the modified montmorillonite is prepared by the following method:

[0020] (1) Mix montmorillonite and deionized water at a mass ratio of 1:10, stir for 1-2 hours, let stand, take the upper suspension, centrifuge, discard the supernatant, wash 3-5 times, and dry to obtain pretreated montmorillonite;

[0021] (2) Pretreated montmorillonite was mixed with 0.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 10 mL, and stirred magnetically at room temperature for 2-3 h. After centrifugation and washing until neutral, activated montmorillonite was obtained.

[0022] (3) The activated montmorillonite obtained in step (2) is mixed with sodium alginate solution with a mass fraction of 0.5-1% at a ratio of 1g:20mL, and magnetically stirred at 30-40℃ for 3-4h. The solid product is collected by centrifugation and washed with deionized water 3-5 times to obtain modified montmorillonite.

[0023] Preferably, the inorganic binder is composed of sodium silicate and metakaolin in a mass ratio of 3:1, and the modulus of sodium silicate is 3.1-3.4.

[0024] Preferably, the additives include 0.3-0.8 parts of dispersant, 0.2-0.5 parts of defoamer, 0.1-0.3 parts of mildew inhibitor and 0.4-1.4 parts of antifreeze.

[0025] The dispersant is one of polyacrylate, polycarboxylate, or modified polyurethane; the defoamer is one of mineral oil, organosilicon, or polyether-modified siloxane defoamers; the mildew inhibitor is one of isothiazolinone, zinc pyridinethione, or benzimidazole mildew inhibitors; and the antifreeze is one of ethylene glycol, propylene glycol, or 1,2-propanediol.

[0026] This invention also provides a method for preparing an inorganic water-based aerogel thermal insulation coating, which includes the following steps:

[0027] Step 1: Under low-speed stirring at 300~500 rpm, add 80% of the formula amount of deionized water to the reactor, then add cellulose ether and auxiliary agents in sequence, and stir for 10~20 minutes to fully dissolve and disperse them.

[0028] Step 2: While maintaining low-speed stirring, slowly add the composite functional filler and half the amount of functional aerogel composite powder. After the addition is complete, increase the speed to 800~1000 rpm and stir for 15~25 minutes to obtain a uniform slurry A.

[0029] Step 3: Reduce the rotation speed to 400-600 rpm, slowly add the styrene-acrylic emulsion, and stir for 5-10 minutes to mix it evenly with slurry A to obtain mixture B;

[0030] Step 4: While stirring at 300-500 rpm, add the inorganic binder to mixture B and stir for 5 minutes to ensure uniform mixing.

[0031] Step 5: Add the remaining functional aerogel composite powder and the remaining deionized water, stir at 400-600 rpm for 10-15 minutes, pass the resulting coating through an 80-mesh sieve, package it, and let it stand for 24 hours to mature, thus obtaining the inorganic waterborne aerogel thermal insulation coating.

[0032] The inorganic binder of this invention is composed of sodium silicate and metakaolin in a mass ratio of 3:1. The sodium silicate modulus is 3.1-3.4, providing good bonding performance and fire resistance. Styrene-acrylic emulsion acts as an organic modifier, enhancing the toughness and adhesion of the coating film. Cellulose ether and additives (dispersant, defoamer, mildew inhibitor, antifreeze) further optimize the stability, workability, and durability of the coating. Through scientific proportioning and process design, a balance between heat insulation, fire resistance, strength, and flexibility is achieved.

[0033] The preparation method employs a step-by-step feeding and low-speed final mixing strategy. First, a portion of the aerogel composite powder and filler are dispersed at a low speed. Then, the emulsion and binder are introduced, and finally, the remaining aerogel is gently mixed in, minimizing the damage to the aerogel structure caused by shear forces. This process ensures the integrity of the aerogel while guaranteeing the uniformity and storage stability of the coating.

[0034] The modified silica aerogel used in this invention is a composite coating solution formed by nanocellulose and aqueous silicone-acrylic emulsion, with the stability of the coating layer enhanced by a carbodiimide crosslinking agent. The silicone-acrylic emulsion serves as the main film-forming agent and flexible bridge; the siloxane segments in its molecular chain have excellent affinity for the hydrophobic SiO2 aerogel surface, allowing it to be firmly adsorbed onto the aerogel surface. The acrylate segments provide film-forming properties and flexibility. Simultaneously, nanocellulose acts as a rigid framework and hydrophilic agent, possessing extremely high specific strength, abundant surface hydroxyl groups, and a nanofiber network structure, enabling it to interact with silica. The silicone-acrylic emulsion interweaves with each other through hydrogen bonding and other interactions, forming a flexible and porous composite coating layer on the aerogel surface. The two work synergistically, with the silicone-acrylic emulsion achieving initial anchoring and flexible encapsulation of the aerogel, while the embedding of nanocellulose enhances the mechanical strength of the coating layer, preventing it from being damaged during subsequent processing. On the other hand, its abundant hydrophilic groups provide the coating layer with lasting hydrophilicity. Most importantly, nanocellulose itself can form a nanoporous structure. This porous coating layer has a low thermal conductivity, thus better preserving the overall thermal insulation performance of the aerogel system.

[0035] This invention relates to a composite functional filler composed of hollow glass microspheres and modified montmorillonite. After acid activation and sodium alginate modification, the modified montmorillonite exhibits a more extended layered structure, resulting in excellent dispersibility and swelling properties in water. These micro- and nano-sized layers can overlap in the coating system, forming a three-dimensional, invisible skeletal network. The hollow glass microspheres, as larger spherical particles, are effectively encapsulated within this three-dimensional skeletal network. The montmorillonite layers fill the gaps between the glass microspheres, making the entire composite filler system more compact and reducing large pores. Furthermore, the modified montmorillonite layers are randomly distributed among the microspheres, and their sheet-like structure elongates the heat transfer path, forcing heat to bypass these layers and forming a more tortuous and complex heat transfer path, thereby significantly reducing the solid-phase heat conduction efficiency.

[0036] When the functional aerogel composite powder of this invention is used in combination with composite functional fillers, the hollow glass microspheres provide micron-level closed pores, while the functional aerogel composite powder provides nano-level open and closed pores. The layered structure of the modified montmorillonite further divides the pores in the system into even finer nano- to submicron-level spaces. This "micron-to-submicron-to-nano" multi-level pore structure can maximize phonon scattering and minimize air convection, thereby achieving synergistic effects and obtaining a lower overall thermal conductivity than using any single filler alone. This allows the waterborne coating of this invention to maintain extremely low thermal conductivity while also possessing excellent bonding strength, crack resistance, and flexibility.

[0037] The beneficial effects of this invention are:

[0038] (1) By modifying silica aerogel, the core problems of aerogel being easy to break and difficult to disperse in aqueous systems are solved.

[0039] (2) The composite functional filler formed by the combination of hollow glass microspheres and modified montmorillonite achieves a synergistic improvement in thermal insulation and mechanical properties.

[0040] (3) Through optimized combination of components, the coating has the characteristics of Class A fire resistance, high bonding strength, good flexibility and ultra-low thermal conductivity. Its comprehensive performance far exceeds that of existing thermal insulation materials, and it is suitable for various energy-saving scenarios such as building exterior walls and industrial equipment. Attached Figure Description

[0041] Figure 1 The images show the surface microstructure of the modified silica aerogel used in this invention before and after modification using SEM images. Detailed Implementation

[0042] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0043] Example 1

[0044] An inorganic water-based aerogel thermal insulation coating is made from the following raw materials in parts by weight: 15 parts of functional aerogel composite powder, 10 parts of composite functional filler, 5 parts of styrene-acrylic emulsion, 20 parts of inorganic binder, 0.1 parts of cellulose ether, 1 part of additives, and 20 parts of water.

[0045] The functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-cell ceramic microspheres in a mass ratio of 3:1; the particle size of the nano-sized closed-cell ceramic microspheres is 50 nm.

[0046] The composite functional filler is composed of hollow glass microspheres and modified montmorillonite at a mass ratio of 2:0.5, and the hollow glass microspheres have a particle size of 10 μm.

[0047] The modified silica aerogel powder is prepared by the following method:

[0048] a. Mix 1 wt% of nanocellulose aqueous dispersion with 10 wt% of aqueous silicone-acrylic emulsion at a mass ratio of 1:3.5, then add 0.1 wt% of crosslinking agent carbodiimide, and stir at low speed until homogeneous to obtain composite coating solution;

[0049] b. Wet the hydrophobic SiO2 aerogel in a small amount of ethanol to obtain a pretreated aerogel;

[0050] c. Slowly add the pretreated aerogel into the composite coating solution at a solid-liquid ratio of 1g:8mL, and stir at a low shear speed of 200rpm for 30 minutes to obtain a mixed slurry.

[0051] d. Heat the mixed slurry at 40℃ for 30-40 minutes and then spray dry it to obtain modified silica aerogel powder.

[0052] The modified montmorillonite is prepared using the following method:

[0053] (1) Mix montmorillonite and deionized water at a mass ratio of 1:10, stir for 1-2 hours, let stand, take the upper suspension, centrifuge, discard the supernatant, wash 3-5 times, and dry to obtain pretreated montmorillonite;

[0054] (2) Pretreated montmorillonite was mixed with 0.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 10 mL, and stirred magnetically at room temperature for 2-3 h. After centrifugation and washing until neutral, activated montmorillonite was obtained.

[0055] (3) The activated montmorillonite obtained in step (2) is mixed with sodium alginate solution with a mass fraction of 0.5% at a ratio of 1g:20mL, and magnetically stirred at 30℃ for 3h. The solid product is collected by centrifugation and washed with deionized water 3-5 times to obtain modified montmorillonite.

[0056] The inorganic binder is composed of sodium silicate and metakaolin in a mass ratio of 3:1, and the modulus of sodium silicate is 3.1.

[0057] The additives include 0.3 parts dispersant, 0.2 parts defoamer, 0.1 parts mildew inhibitor, and 0.4 parts antifreeze. The dispersant is polyacrylate; the defoamer is mineral oil; the mildew inhibitor is isothiazolinone mildew inhibitor; and the antifreeze is ethylene glycol.

[0058] A method for preparing an inorganic water-based aerogel thermal insulation coating, comprising the following steps:

[0059] Step 1: Under low-speed stirring at 300 rpm, add 80% of the formula amount of deionized water to the reactor, then add cellulose ether and auxiliary agents in sequence, and stir for 10-20 minutes to fully dissolve and disperse them.

[0060] Step 2: While maintaining low-speed stirring, slowly add the composite functional filler and half the amount of functional aerogel composite powder. After the addition is complete, increase the speed to 800 rpm and stir for 15-25 minutes to obtain a uniform slurry A.

[0061] Step 3: Reduce the rotation speed to 400 rpm, slowly add the styrene-acrylic emulsion, and stir for 5-10 minutes to mix it evenly with slurry A to obtain mixture B;

[0062] Step 4: While stirring at 300 rpm, add the inorganic binder to mixture B and stir for 5 minutes to ensure uniform mixing.

[0063] Step 5: Add the remaining functional aerogel composite powder and the remaining deionized water, stir at 400 rpm for 10-15 minutes, pass the resulting coating through an 80-mesh sieve, package it, and let it stand for 24 hours to mature, thus obtaining the inorganic waterborne aerogel thermal insulation coating.

[0064] Example 2

[0065] An inorganic water-based aerogel thermal insulation coating is made from the following raw materials in parts by weight: 35 parts of functional aerogel composite powder, 25 parts of composite functional filler, 15 parts of styrene-acrylic emulsion, 40 parts of inorganic binder, 0.5 parts of cellulose ether, 3 parts of additives, and 35 parts of water.

[0066] The functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-cell ceramic microspheres in a mass ratio of 4:1; the particle size of the nano-sized closed-cell ceramic microspheres is 200 nm.

[0067] The composite functional filler is composed of hollow glass microspheres and modified montmorillonite in a mass ratio of 2:1, and the hollow glass microspheres have a particle size of 30 μm.

[0068] The modified silica aerogel powder is prepared by the following method:

[0069] a. Mix 3 wt% of nanocellulose aqueous dispersion with 15 wt% of aqueous silicone-acrylic emulsion at a mass ratio of 1:3, then add 0.3 wt% of crosslinking agent carbodiimide, and stir at low speed until homogeneous to obtain composite coating solution;

[0070] b. Wet the hydrophobic SiO2 aerogel in a small amount of ethanol to obtain a pretreated aerogel;

[0071] c. Slowly add the pretreated aerogel into the composite coating solution at a solid-liquid ratio of 1g:10mL, and stir at a low shear speed of 400rpm for 30-60 minutes to obtain a mixed slurry;

[0072] d. After heating the mixed slurry at 45℃ for 30-40 minutes, spray dry it to obtain modified silica aerogel powder.

[0073] The modified montmorillonite is prepared using the following method:

[0074] (1) Mix montmorillonite and deionized water at a mass ratio of 1:10, stir for 1-2 hours, let stand, take the upper suspension, centrifuge, discard the supernatant, wash 3-5 times, and dry to obtain pretreated montmorillonite;

[0075] (2) Pretreated montmorillonite was mixed with 0.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 10 mL, and stirred magnetically at room temperature for 2-3 h. After centrifugation and washing until neutral, activated montmorillonite was obtained.

[0076] (3) The activated montmorillonite obtained in step (2) is mixed with a sodium alginate solution with a mass fraction of 1% at a ratio of 1g:20mL, and magnetically stirred at 30℃ for 3-4h. The solid product is collected by centrifugation and washed with deionized water 3-5 times to obtain modified montmorillonite.

[0077] The inorganic binder is composed of sodium silicate and metakaolin in a mass ratio of 3:1, and the modulus of sodium silicate is 3.2.

[0078] The additives include 0.5 parts of dispersant, 0.4 parts of defoamer, 0.2 parts of mildew inhibitor, and 1.0 part of antifreeze. The dispersant is a polycarboxylate; the defoamer is an organosilicon; the mildew inhibitor is zinc pyridinethione mildew inhibitor; and the antifreeze is propylene glycol.

[0079] A method for preparing an inorganic water-based aerogel thermal insulation coating, comprising the following steps:

[0080] Step 1: Under low-speed stirring at 500 rpm, add 80% of the formula amount of deionized water to the reactor, then add cellulose ether and auxiliary agents in sequence, and stir for 10-20 minutes to fully dissolve and disperse them.

[0081] Step 2: While maintaining low-speed stirring, slowly add the composite functional filler and half the amount of functional aerogel composite powder. After the addition is complete, increase the speed to 1000 rpm and stir for 15-25 minutes to obtain a uniform slurry A.

[0082] Step 3: Reduce the rotation speed to 600 rpm, slowly add the styrene-acrylic emulsion, and stir for 5-10 minutes to mix it evenly with slurry A to obtain mixture B;

[0083] Step 4: While stirring at 300-500 rpm, add the inorganic binder to mixture B and stir for 5 minutes to ensure uniform mixing.

[0084] Step 5: Add the remaining functional aerogel composite powder and the remaining deionized water, stir at 400-600 rpm for 10-15 minutes, pass the resulting coating through an 80-mesh sieve, package it, and let it stand for 24 hours to mature, thus obtaining the inorganic waterborne aerogel thermal insulation coating.

[0085] Example 3

[0086] An inorganic water-based aerogel thermal insulation coating is made from the following raw materials in parts by weight: 30 parts of functional aerogel composite powder, 20 parts of composite functional filler, 10 parts of styrene-acrylic emulsion, 30 parts of inorganic binder, 0.3 parts of cellulose ether, 2 parts of additives, and 30 parts of water.

[0087] The functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-cell ceramic microspheres in a mass ratio of 5:1; the particle size of the nano-sized closed-cell ceramic microspheres is 500 nm.

[0088] The composite functional filler is composed of hollow glass microspheres and modified montmorillonite at a mass ratio of 2:0.8, and the hollow glass microspheres have a particle size of 50 μm.

[0089] The modified silica aerogel powder is prepared by the following method:

[0090] a. Mix 5 wt% of nanocellulose aqueous dispersion with 20 wt% of aqueous silicone-acrylic emulsion at a mass ratio of 1:3, then add 0.3 wt% of crosslinking agent carbodiimide, and stir at low speed until uniform to obtain composite coating solution;

[0091] b. Wet the hydrophobic SiO2 aerogel in a small amount of ethanol to obtain a pretreated aerogel;

[0092] c. Slowly add the pretreated aerogel to the composite coating solution at a solid-liquid ratio of 1g:10mL, and stir at a low shear speed of 500rpm for 30-60 minutes to obtain a mixed slurry;

[0093] d. The mixed slurry is heated at 42°C for 35 minutes and then spray-dried to obtain modified silica aerogel powder.

[0094] The modified montmorillonite is prepared using the following method:

[0095] (1) Mix montmorillonite and deionized water at a mass ratio of 1:10, stir for 1-2 hours, let stand, take the upper suspension, centrifuge, discard the supernatant, wash 3-5 times, and dry to obtain pretreated montmorillonite;

[0096] (2) Pretreated montmorillonite was mixed with 0.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 10 mL, and stirred magnetically at room temperature for 2-3 h. After centrifugation and washing until neutral, activated montmorillonite was obtained.

[0097] (3) The activated montmorillonite obtained in step (2) is mixed with sodium alginate solution with a mass fraction of 0.8% at a ratio of 1g:20mL, and magnetically stirred at 35℃ for 3-4h. The solid product is collected by centrifugation and washed with deionized water 3-5 times to obtain modified montmorillonite.

[0098] The inorganic binder is composed of sodium silicate and metakaolin in a mass ratio of 3:1, and the modulus of sodium silicate is 3.3.

[0099] The additives include 0.5 parts dispersant, 0.4 parts defoamer, 0.2 parts mildew inhibitor, and 1.4 parts antifreeze. The dispersant is modified polyurethane; the defoamer is a polyether-modified siloxane defoamer; the mildew inhibitor is a benzimidazole mildew inhibitor; and the antifreeze is 1,2-propanediol.

[0100] A method for preparing an inorganic water-based aerogel thermal insulation coating, comprising the following steps:

[0101] Step 1: Under low-speed stirring at 00 rpm, add 80% of the formula amount of deionized water to the reactor, then add cellulose ether and auxiliary agents in sequence, and stir for 10-20 minutes to fully dissolve and disperse them.

[0102] Step 2: While maintaining low-speed stirring, slowly add the composite functional filler and half the amount of functional aerogel composite powder. After the addition is complete, increase the speed to 9000 rpm and stir for 15-25 minutes to obtain a uniform slurry A.

[0103] Step 3: Reduce the rotation speed to 500 rpm, slowly add the styrene-acrylic emulsion, and stir for 5-10 minutes to mix it evenly with slurry A to obtain mixture B;

[0104] Step 4: While stirring at 400 rpm, add the inorganic binder to mixture B and stir for 5 minutes to ensure uniform mixing.

[0105] Step 5: Add the remaining functional aerogel composite powder and the remaining deionized water, stir at 400-600 rpm for 10-15 minutes, pass the resulting coating through an 80-mesh sieve, package it, and let it stand for 24 hours to mature, thus obtaining the inorganic waterborne aerogel thermal insulation coating.

[0106] Example 4

[0107] An inorganic water-based aerogel thermal insulation coating is made from the following raw materials in parts by weight: 25 parts of functional aerogel composite powder, 15 parts of composite functional filler, 10 parts of styrene-acrylic emulsion, 30 parts of inorganic binder, 0.3 parts of cellulose ether, 3 parts of additives, and 25 parts of water.

[0108] The functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-cell ceramic microspheres in a mass ratio of 5:1; the particle size of the nano-sized closed-cell ceramic microspheres is 200 nm.

[0109] The composite functional filler is composed of hollow glass microspheres and modified montmorillonite in a mass ratio of 2:0.6, and the hollow glass microspheres have a particle size of 10 μm.

[0110] The modified silica aerogel powder is prepared by the following method:

[0111] a. Mix 2 wt% of nanocellulose aqueous dispersion with 18 wt% of aqueous silicone-acrylic emulsion at a mass ratio of 1:2.5, then add 0.3 wt% of crosslinking agent carbodiimide, and stir at low speed until homogeneous to obtain composite coating solution;

[0112] b. Wet the hydrophobic SiO2 aerogel in a small amount of ethanol to obtain a pretreated aerogel;

[0113] c. Slowly add the pretreated aerogel to the composite coating solution at a solid-liquid ratio of 1g:10mL, and stir at a low shear rate of 200-500 rpm for 30-60 minutes to obtain a mixed slurry;

[0114] d. After heating the mixed slurry at 45℃ for 30-40 minutes, spray dry it to obtain modified silica aerogel powder.

[0115] The modified montmorillonite is prepared using the following method:

[0116] (1) Mix montmorillonite and deionized water at a mass ratio of 1:10, stir for 1-2 hours, let stand, take the upper suspension, centrifuge, discard the supernatant, wash 3-5 times, and dry to obtain pretreated montmorillonite;

[0117] (2) Pretreated montmorillonite was mixed with 0.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 10 mL, and stirred magnetically at room temperature for 2-3 h. After centrifugation and washing until neutral, activated montmorillonite was obtained.

[0118] (3) The activated montmorillonite obtained in step (2) is mixed with sodium alginate solution with a mass fraction of 0.7% at a ratio of 1g:20mL, and magnetically stirred at 38℃ for 3-4h. The solid product is collected by centrifugation and washed with deionized water 3-5 times to obtain modified montmorillonite.

[0119] The inorganic binder is composed of sodium silicate and metakaolin in a mass ratio of 3:1, and the modulus of sodium silicate is 3.4.

[0120] The additives include 0.5 parts of dispersant, 0.3 parts of defoamer, 0.1 parts of mildew inhibitor, and 0.8 parts of antifreeze. The dispersant is a polycarboxylate; the defoamer is an organosilicon defoamer; the mildew inhibitor is an isothiazolinone mildew inhibitor; and the antifreeze is ethylene glycol.

[0121] A method for preparing an inorganic water-based aerogel thermal insulation coating, comprising the following steps:

[0122] Step 1: Under low-speed stirring at 300 rpm, add 80% of the formula amount of deionized water to the reactor, then add cellulose ether and auxiliary agents in sequence, and stir for 10-20 minutes to fully dissolve and disperse them.

[0123] Step 2: While maintaining low-speed stirring, slowly add the composite functional filler and half the amount of functional aerogel composite powder. After the addition is complete, increase the speed to 800 rpm and stir for 15-25 minutes to obtain a uniform slurry A.

[0124] Step 3: Reduce the rotation speed to 400 rpm, slowly add the styrene-acrylic emulsion, and stir for 5-10 minutes to mix it evenly with slurry A to obtain mixture B;

[0125] Step 4: While stirring at 300 rpm, add the inorganic binder to mixture B and stir for 5 minutes to ensure uniform mixing.

[0126] Step 5: Add the remaining functional aerogel composite powder and the remaining deionized water, stir at 500 rpm for 10-15 minutes, pass the resulting coating through an 80-mesh sieve, package it, and let it stand for 24 hours to mature, thus obtaining the inorganic waterborne aerogel thermal insulation coating.

[0127] Comparative Example 1

[0128] An inorganic water-based aerogel thermal insulation coating, whose raw material composition and preparation method are basically the same as those in Example 1, the only difference being that the functional aerogel composite powder is composed of silica aerogel powder and nano-sized closed-pore ceramic microspheres, and the silica aerogel powder has not undergone any modification treatment.

[0129] Comparative Example 2

[0130] An inorganic water-based aerogel thermal insulation coating, whose raw material composition and preparation method are basically the same as those in Example 1, the only difference being that: in the composite functional filler, ordinary montmorillonite that has not been acid-activated and modified with sodium alginate is used instead of modified montmorillonite.

[0131] Comparative Example 3

[0132] An inorganic water-based aerogel thermal insulation coating, whose raw material composition and preparation method are basically the same as those in Example 1, the only difference being that: the silica aerogel powder in the functional aerogel composite powder has not undergone any modification treatment and is replaced by ordinary silica aerogel; at the same time, in the composite functional filler, ordinary montmorillonite that has not undergone acid activation and sodium alginate modification is used to replace modified montmorillonite.

[0133] Comparative Example 4

[0134] An inorganic water-based aerogel thermal insulation coating, whose raw material composition and preparation method are basically the same as those in Example 1, the only difference being that the functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-pore ceramic microspheres in a mass ratio of 2:1.

[0135] Comparative Example 5

[0136] An inorganic water-based aerogel thermal insulation coating, whose raw material composition and preparation method are basically the same as those in Example 1, the only difference being that the functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-pore ceramic microspheres in a mass ratio of 6:1.

[0137] Performance testing

[0138] The surface microstructure of the modified silica aerogel used in this invention before and after modification was characterized, specifically as follows: Figure 1 As shown. From Figure 1 It can be observed that the unmodified silica aerogel is a nano-porous structure formed by the interconnection of nano-SiO2 particles. Figure 1 a); The morphology of the modified silica aerogel changed significantly ( Figure 1 (b) The nano-silica particles and the nano-cellulose fiber network form an interpenetrating network structure, making the modified aerogel structure increasingly dense.

[0139] The coating samples obtained in Examples 1-4 and Comparative Examples 1-5 were subjected to performance tests, including thermal conductivity, bond strength, flexibility, fire resistance and weather resistance.

[0140] Thermal conductivity: The thermal conductivity of the coating after drying and forming a film was tested using the hot wire method at 25℃ and 50% relative humidity.

[0141] Bond strength: According to JG / T 158-2013, a tensile bond strength tester was used;

[0142] Flexibility: According to GB / T 1731-2020, bend the coating around a steel rod with a diameter of 2mm and observe whether it cracks;

[0143] Fire resistance rating: Tested according to GB 8624-2012 "Classification of Combustion Performance of Building Materials and Products";

[0144] Weather resistance: A xenon lamp aging chamber (1000h accelerated aging) was used. After the test, the coating condition was checked and the adhesion strength retention rate was measured. The test results are shown in Table 1.

[0145] Table 1 Test Results

[0146]

[0147] As shown in Table 1, the thermal conductivity of each embodiment of the present invention ranges from 0.025 to 0.028 W / (m·K), exhibiting excellent thermal insulation performance. In contrast, the thermal conductivity of Comparative Examples 1 and 3 is significantly higher, indicating that coating modification of the aerogel and modification of montmorillonite are crucial for preserving its nanoporous structure and constructing an efficient thermal insulation network. Meanwhile, the bonding strength of Examples 1-4 of the present invention is ≥0.85 MPa, and all flexibility tests passed, demonstrating a balance between high bonding strength and good flexibility. The bonding strength of Comparative Examples 1 and 3 is less than 0.5 MPa, and their flexibility is poor, indicating that the unmodified aerogel is easily broken and has weak bonding with the matrix. The bonding strength of Comparative Examples 4 and 5 is significantly lower than that of the Example Group, indicating that changing the ratio of the two raw materials in the functional aerogel composite powder of the present invention significantly worsens the performance of the coating, and the mass ratio of the functional aerogel composite powder of the present invention is within the optimal range. After 1000 hours of accelerated aging, the bond strength retention rates of Examples 1-4 of this invention were all greater than 90%, demonstrating excellent durability. In contrast, the retention rates of Comparative Examples 1-5 decreased, especially Comparative Examples 1 and 3, where the retention rates were below 80%, indicating that the modified process and formulation system of this invention effectively improved the long-term service stability of the coating. The above data fully demonstrate that this invention, through the synergistic design of functional aerogel composite powder and composite functional filler, and the gentle step-by-step feeding process, successfully prepared an inorganic water-based thermal insulation coating with ultra-low thermal conductivity, high bond strength, excellent flexibility, and durability. Its overall performance is significantly superior to the control samples without modification or optimized formulation of key components.

[0148] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. An inorganic water-based aerogel thermal insulation coating, characterized in that, It is made from the following raw materials in parts by weight: 15-35 parts of functional aerogel composite powder, 10-25 parts of composite functional filler, 5-15 parts of styrene-acrylic emulsion, 20-40 parts of inorganic binder, 0.1-0.5 parts of cellulose ether, 1-3 parts of additives, and 20-35 parts of water. The functional aerogel composite powder is composed of modified silica aerogel powder and nano-sized closed-pore ceramic microspheres in a mass ratio of (3~5):

1. The composite functional filler is composed of hollow glass microspheres and modified montmorillonite in a mass ratio of 2:(0.5-1), and the particle size of the hollow glass microspheres is 10-50μm; The modified silica aerogel powder is prepared by the following method: a. Mix 1-5 wt% of nanocellulose aqueous dispersion with 10-20 wt% of aqueous silicone-acrylic emulsion at a mass ratio, then add 0.1-0.5 wt% of crosslinking agent and stir at low speed until homogeneous to obtain composite coating solution; b. Wet the hydrophobic SiO2 aerogel in a small amount of ethanol to obtain a pretreated aerogel; c. Slowly add the pretreated aerogel to the composite coating solution and stir at a low shear rate of 200-500 rpm for 30-60 minutes to obtain a mixed slurry; d. After heating the mixed slurry at 40-45℃ for 30-40 minutes, spray dry it to obtain modified silica aerogel powder; The modified montmorillonite is prepared using the following method: (1) Mix montmorillonite and deionized water at a mass ratio of 1:10, stir for 1-2 hours, let stand, take the upper suspension, centrifuge, discard the supernatant, wash 3-5 times, and dry to obtain pretreated montmorillonite; (2) Pretreated montmorillonite was mixed with 0.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 10 mL, and stirred magnetically at room temperature for 2-3 h. After centrifugation and washing until neutral, activated montmorillonite was obtained. (3) The activated montmorillonite obtained in step (2) is mixed with sodium alginate solution with a mass fraction of 0.5-1% at a ratio of 1g:20mL, and magnetically stirred at 30-40℃ for 3-4h. The solid product is collected by centrifugation and washed with deionized water 3-5 times to obtain modified montmorillonite.

2. The inorganic water-based aerogel thermal insulation coating according to claim 1, characterized in that, In step a, the mass ratio of the nanocellulose aqueous dispersion to the aqueous silicone-acrylic emulsion is 1:(2-3.5).

3. The inorganic water-based aerogel thermal insulation coating according to claim 1, characterized in that, The crosslinking agent is carbodiimide.

4. The inorganic water-based aerogel thermal insulation coating according to claim 1, characterized in that, In step c, the solid-liquid ratio of the pretreated aerogel to the composite coating liquid is 1g:(8-10)mL.

5. The inorganic water-based aerogel thermal insulation coating according to claim 1, characterized in that, The particle size of the nanoscale closed-pore ceramic microspheres is 50~500nm.

6. The inorganic water-based aerogel thermal insulation coating according to claim 1, characterized in that, The inorganic binder is composed of sodium silicate and metakaolin in a mass ratio of 3:1, and the modulus of sodium silicate is 3.1-3.

4.

7. The inorganic water-based aerogel thermal insulation coating according to claim 1, characterized in that, The additives include 0.3-0.8 parts of dispersant, 0.2-0.5 parts of defoamer, 0.1-0.3 parts of mildew inhibitor and 0.4-1.4 parts of antifreeze.

8. A method for preparing an inorganic water-based aerogel thermal insulation coating according to any one of claims 1-7, characterized in that, It includes the following steps: Step 1: Under low-speed stirring at 300~500 rpm, add 80% of the formula amount of deionized water to the reactor, then add cellulose ether and auxiliary agents in sequence, and stir for 10~20 minutes to fully dissolve and disperse them. Step 2: While maintaining low-speed stirring, slowly add the composite functional filler and half the amount of functional aerogel composite powder. After the addition is complete, increase the speed to 800~1000 rpm and stir for 15~25 minutes to obtain a uniform slurry A. Step 3: Reduce the rotation speed to 400-600 rpm, slowly add the styrene-acrylic emulsion, and stir for 5-10 minutes to mix it evenly with slurry A to obtain mixture B; Step 4: While stirring at 300-500 rpm, add the inorganic binder to mixture B and stir for 5 minutes to ensure uniform mixing. Step 5: Add the remaining functional aerogel composite powder and the remaining deionized water, stir at 400-600 rpm for 10-15 minutes, pass the resulting coating through an 80-mesh sieve, package it, and let it stand for 24 hours to mature, thus obtaining the inorganic waterborne aerogel thermal insulation coating.

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