Inorganic matter coated silicon dioxide aerogel composite material as well as preparation method and application thereof

Abstract

The invention provides an inorganic matter coated silicon dioxide aerogel composite material as well as a preparation method and application thereof. The composite material comprises a hydrophobic inner core and a hydrophilic shell coating the inner core, the inner core comprises hydrophobic silicon dioxide aerogel, and the shell comprises hydrophilic inorganic oxide aerogel. The aerogel composite material is suitable for a water-based paint system, can be well dispersed in the water-based paint system on the premise of not adding other wetting dispersants, and can be added in a large amount, and after the addition amount exceeds 5%, the appearance of a coating is still kept good, and no cracking phenomenon exists.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat-insulating and heat-preserving coatings in the sub-field of heat-insulating and heat-preserving materials, and particularly relates to an inorganic-coated silica aerogel, a preparation method thereof, and an application thereof. Background Art

[0002] Aerogel is a commonly used heat-insulating material. 95% - 97% of its volume consists of nanoscale pores. The existence of these pores makes aerogel very good at "thermal insulation", and its thermal conductivity can be as low as 0.018 w / k.m. Among them, silica aerogel has a large market share and is a hot spot for the development and application of various forms of heat-insulating and heat-preserving materials. Currently, most commercially available silica aerogels are treated hydrophobic types. Because untreated silica aerogel will cause its structure to collapse and fail when encountering water, for applications that need to be used in a water (moisture) environment, it is usually necessary to hydrophobize the silica aerogel.

[0003] The silica aerogel used in the field of heat-insulating and heat-preserving coatings is in powder form. As a heat-insulating component, aerogel powder usually needs to be added in sufficient amounts to greatly reduce the thermal conductivity of the coating. However, in a water-based coating system, a large amount of hydrophobic silica aerogel cannot be well compatible with the coating system. Currently, the prior art usually uses wetting and dispersing agents in the coating system to enable a large amount of hydrophobic silica to be added, but this will lead to a decrease in the water resistance of the coating. In addition, due to the low density of aerogel powder (for example, 0.05 - 0.12 g / cm 3 ), and high specific surface area (for example, 800 - 1000 m 2 / g), after adding a certain amount (for example, reaching 5 wt%) in the coating, it will cause the dried coating to crack, thus affecting its use.

[0004] Currently, the existing technologies usually adopt the method of organic coating or modification to improve silica aerogel. For example, Chinese Patent CN107266996 B (October 30, 2020) discloses a method for surface coating of hydrophobic aerogel powder, coating with a fluorine-containing acrylic film. The method is to first make a water emulsion of the hydrophobic aerogel powder with an emulsifier, then dry it, and then perform surface treatment with fluorine-containing acrylic plasma to form a coating film. The equipment and process are complex. Chinese Patent CN116023804 A (April 28, 2023) discloses a method for preparing silica aerogel microcapsules. Its technical feature is to spray a low surface tension liquid on the aerogel powder before liquid resin coating, then add it to the water emulsion containing an emulsifier. After good dispersion, add a water-soluble melamine prepolymer for heating reaction to obtain a modified silica aerogel microcapsule emulsion; separate, purify, and dry the microcapsule emulsion to obtain silica aerogel microcapsules. Chinese Patent CN115010841 B (December 5, 2023) discloses a surface grafting technology for silica aerogel powder, that is, introducing an acrylic structure on the surface of silica aerogel to increase its dispersibility and compatibility with the subsequent acrylic emulsion. The aerogel prepared by the above-mentioned method of organic coating or modification usually also needs to add wetting agents and dispersants in the water-based coating system to disperse a large amount of aerogel in the water-based coating. Summary of the Invention

[0005] To solve all or part of the above technical problems, the present invention provides the following technical solutions: One of the purposes of the present invention is to provide an inorganic-coated silica aerogel composite material, the composite material includes a hydrophobic core and a hydrophilic shell coating the core, the core includes a hydrophobic silica aerogel, and the shell includes a hydrophilic inorganic oxide aerogel.

[0006] In some embodiments, the composition of the inorganic oxide aerogel includes metal oxides and / or silicon oxides.

[0007] Further, the metal oxides include one or more of titanium dioxide, zirconium dioxide, and aluminum oxide; the silicon oxides include silica.

[0008] In some embodiments, the inorganic oxide aerogel is formed in-situ on the surface of the silica aerogel by sol-gel reaction of metal alkoxide compounds and / or silicate compounds in a mixed solvent.

[0009] Another object of the present invention is to provide a method for preparing an inorganic-coated silica aerogel composite material, and the preparation method includes: subjecting a mixed reaction system containing a metal alkoxide compound and / or a silicate compound, a hydrophobic silica aerogel, a catalyst, and a mixed solvent to a sol-gel reaction. During the reaction process, the metal alkoxide compound and / or the silicate compound are coated on the surface of the hydrophobic silica aerogel through hydrolysis and polycondensation reactions to obtain a composite gel; and drying the composite gel to obtain an inorganic-coated silica aerogel composite material.

[0010] In some embodiments, the mixed solvent includes an organic solvent and water, and the organic solvent includes an alcohol and / or an alcohol ether.

[0011] Further, the alcohol includes one or more combinations of methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, and butylene glycol, and the alcohol ether includes one or more combinations of ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether.

[0012] Further, in the mixed solvent, the mass ratio of water to the organic solvent is 10-25:5-15.

[0013] In some embodiments, the metal alkoxide compound includes one or more combinations of titanium tetraisopropoxide, zirconium n-propoxide, and aluminum isopropoxide; the silicate compound includes one or more combinations of methyl orthosilicate, ethyl orthosilicate, and ethyl polysilicate.

[0014] In some embodiments, the catalyst includes one or more combinations of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, ammonia water, sodium hydroxide, ethylenediamine, and hexamethylenediamine.

[0015] In some embodiments, in the mixed reaction system, the mass ratio of the metal alkoxide compound and / or the silicate compound, the organic solvent, and the silica aerogel is 2-5:3-15:1.

[0016] In some embodiments, in the mixed reaction system, the mass ratio of water, the organic solvent, and the catalyst is 10-25:5-15:1-3.

[0017] In some embodiments, the temperature of the sol-gel reaction is 20-50 °C.

[0018] In some embodiments, the time of the sol-gel reaction is 1-2 h.

[0019] In some embodiments, the drying is spray drying.

[0020] Further, the spray dryer used for the spray drying is a laboratory type, the inlet air temperature of the spray chamber is 200 - 300 °C, and the nozzle diameter is 0.75 - 2 mm.

[0021] In a typical embodiment, the preparation method includes the following steps: First, dilute the metal alkoxide compound and / or silicate compound with an alcohol and / or alcohol ether solvent, and then add the hydrophobic silica aerogel powder, and uniformly mix to obtain a first mixture; Provide a second mixture containing water, alcohol and / or alcohol ether and a catalyst, add the first mixture to the second mixture and mix uniformly to obtain a mixed reaction system; Control the reaction temperature of the mixed reaction system to be 20 - 50 °C to carry out the sol-gel reaction to obtain a composite gel; Perform spray drying on the composite gel to obtain an inorganic-coated silica aerogel composite material.

[0022] A third object of the present invention is to provide an inorganic-coated silica aerogel composite material obtained by the preparation method according to any one of the above technical solutions.

[0023] A fourth object of the present invention is to provide the application of the inorganic-coated silica aerogel composite material according to any one of the above technical solutions in the preparation of an aqueous coating, and the coating formed by the aqueous coating has at least a heat insulation function.

[0024] A fifth object of the present invention is to provide an aqueous heat insulation coating, including the inorganic-coated silica aerogel composite material according to any one of the above technical solutions.

[0025] In some embodiments, the content of the inorganic-coated silica aerogel composite material is more than 10%. Preferably, it is more than 20%.

[0026] A sixth object of the present invention is to provide a heat insulation coating, and the heat insulation coating is formed by the aqueous heat insulation coating according to any one of the above technical solutions.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The aerogel composite material provided by the present invention has a hydrophilic outer shell and a hydrophobic inner core. While being able to resist moisture damage, the composite material can be applied to an aqueous coating system. Without the addition of other wetting and dispersing agents, it can be well dispersed in the aqueous coating system and can be added in large amounts. After the addition amount exceeds 5%, the coating appearance remains good without cracking; (2) The inorganic-coated silica aerogel composite material provided by the present invention has stable chemical properties, high mechanical strength, and the coated hydrophilic shell has stable chemical properties and high mechanical strength; (3) The preparation method provided by the present invention has a simple process and is suitable for industrial production. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 is the water contact angle of the hydrophobic silica aerogel without coating treatment in Example 1 of the present invention; Figure 2 is the water contact angle of the aerogel composite material after coating in Example 1 of the present invention; Figure 3 is a picture of the hydrophobic silica aerogel without coating treatment in Example 1 of the present invention dispersed in water.

[0030] Figure 4 is a picture of the aerogel composite material after coating in Example 1 of the present invention dispersed in water. Specific Embodiments

[0031] The following will specifically describe the technical solutions of the present invention in detail in combination with specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. The specific functional details disclosed herein should not be construed as restrictive, but only as the basis of the claims and as a representative basis for teaching those skilled in the art to adopt the present invention in any appropriate detailed embodiment in fact.

[0032] Example 1 Take a container and add 30 g of tetraethyl orthosilicate and 80 g of ethanol, stir evenly, slowly add 10 g of hydrophobic silica aerogel powder and stir evenly to form a paste-like aerogel; Add 220 g of water, 90 g of ethanol, and 20 g of hydrochloric acid with a concentration of 37 wt% to a reaction kettle with temperature control and stirring, heat up to 50 °C and keep it, slowly add the above paste-like aerogel, and react for 4 hours under medium-speed stirring. After the reaction is completed, pour it into a container and let it stand for 24 hours, and then perform spray drying. The inlet air temperature of the spray chamber is 250 °C to obtain a silica-coated aerogel composite material powder.

[0033] Figure 1is the water contact angle of the uncoated hydrophobic silica aerogel, which is 151°. Figure 2 is the water contact angle of the coated aerogel composite, which is 117°. Figure 3 is a picture of the uncoated hydrophobic silica aerogel dispersed in water. It can be seen that the uncoated hydrophobic silica aerogel cannot be wetted by water. Figure 4 is a picture of the coated aerogel composite dispersed in water. It can be seen that the coated aerogel composite is wetted by water and is compatible with water.

[0034] Use the above hydrophobic silica aerogel powder coated with silica to prepare a water-based thermal insulation coating, and prepare the water-based thermal insulation coating into a coating.

[0035] Example 2 Take a container, add 30 g of tetraethyl orthosilicate and 80 g of ethanol, stir evenly, slowly add 10 g of hydrophobic silica aerogel powder and stir evenly to form a paste-like aerogel; Add 220 g of water, 90 g of ethanol, and 30 g of 26 wt% ammonia water to a reaction kettle with temperature control and stirring, heat up to 50 °C and keep it, and slowly add the above paste-like aerogel; react for 4 hours under medium-speed stirring conditions, pour it into a container after the reaction and let it stand for 24 hours, and then carry out spray drying. The inlet air temperature of the spray chamber is 250 °C to obtain a silica-coated aerogel composite powder.

[0036] Prepare the coating and the coating by the same method as in Example 1.

[0037] Example 3 Take a container, add 30 g of titanium isopropoxide and 80 g of isopropanol, stir evenly, slowly add 10 g of hydrophobic silica aerogel powder and stir evenly to form a paste-like aerogel; Add 220 g of water, 90 g of isopropanol, and 30 g of 26 wt% ammonia water to a reaction kettle with temperature control and stirring, heat up to 50 °C and keep it, and slowly add the above paste-like aerogel; react for 4 hours under medium-speed stirring conditions, pour it into a container after the reaction and let it stand for 24 hours, and then carry out spray drying. The inlet air temperature of the spray chamber is 250 °C to obtain a titanium dioxide-coated aerogel composite powder.

[0038] Prepare the coating and the coating by the same method as in Example 1.

[0039] Example 4 Take a container, add 20 g of zirconium n-propoxide and 80 g of ethanol, stir evenly, slowly add 10 g of hydrophobic silica aerogel powder and stir evenly to form a paste-like aerogel; Add 100 g of water, 50 g of ethanol, and 10 g of hydrochloric acid with a concentration of 37 wt% into a reaction kettle with temperature control and stirring. Control the temperature at 20 °C, and slowly add the above-mentioned paste-like aerogel. React for 4 hours under medium-speed stirring conditions. After the reaction is completed, pour it into a container and let it stand for 24 hours, and then perform spray drying. The inlet air temperature of the spray chamber is 250 °C to obtain a powder of aerogel composite material coated with zirconia.

[0040] Prepare the coating and the coating layer by the same method as in Example 1.

[0041] Example 5 Take a container, add 50 g of zirconium propoxide and 80 g of ethanol, stir evenly, slowly add 10 g of hydrophobic silica aerogel powder and stir evenly to form a paste-like aerogel; Add 250 g of water, 150 g of ethanol, and 20 g of hydrochloric acid with a concentration of 37 wt% into a reaction kettle with temperature control and stirring. Control the temperature at 40 °C, and slowly add the above-mentioned paste-like aerogel. React for 4 hours under medium-speed stirring conditions. After the reaction is completed, pour it into a container and let it stand for 24 hours, and then perform spray drying. The inlet air temperature of the spray chamber is 250 °C to obtain a powder of aerogel composite material coated with zirconia.

[0042] Prepare the coating and the coating layer by the same method as in Example 1.

[0043] All aspects, embodiments, features, and examples of the present invention should be considered illustrative in all respects and are not intended to limit the present invention. The scope of the present invention is only defined by the claims. Without departing from the spirit and scope of the claimed invention, those skilled in the art will appreciate other embodiments, modifications, and uses.

[0044] In addition, the inventors of this case also referred to the foregoing embodiments and conducted tests with other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0045] Although the present invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the present invention, and elements of the embodiments can be replaced with substantial equivalents. Additionally, many modifications can be made without departing from the scope of the present invention to adapt a particular situation or material to the teachings of the present invention. Therefore, the present invention is not intended to be limited to the specific embodiments disclosed for carrying out the present invention, but is intended to cover all embodiments falling within the scope of the appended claims. Furthermore, unless specifically stated, any use of the terms first, second, etc. does not denote any order or importance, but the terms first, second, etc. are used to distinguish one element from another.

Claims

1. An inorganic-coated silica aerogel composite material, characterized in that: The composite material comprises a hydrophobic core and a hydrophilic shell covering the core, wherein the core comprises hydrophobic silica aerogel, and the shell comprises hydrophilic inorganic oxide aerogel.

2. The composite material according to claim 1, characterized in that: The inorganic oxide aerogel comprises metal oxide and / or silicon oxide; preferably, the metal oxide comprises one or more of titanium dioxide, zirconium dioxide and aluminum oxide; the silicon oxide comprises silicon dioxide; And / or, the inorganic oxide aerogel is formed in situ on the surface of the silica aerogel by a sol-gel reaction of a metal alkoxide compound and / or a silicate compound in a mixed solvent.

3. A method for preparing an inorganic-coated silica aerogel composite material, characterized in that: include: A mixed reaction system containing a metal alkoxy compound and / or a silicate compound, a hydrophobic silica aerogel, a catalyst and a mixed solvent is subjected to a sol-gel reaction. During the reaction, the metal alkoxy compound and / or the silicate compound is coated on the surface of the hydrophobic silica aerogel through hydrolysis and polycondensation to obtain a composite gel; and the composite gel is dried to obtain an inorganic-coated silica aerogel composite material.

4. The preparation method according to claim 3, characterized in that: Specifically include: The mixed solvent comprises an organic solvent and water, wherein the organic solvent comprises alcohol and / or alcohol ether; And / or, the metal alkoxide compound includes one or more of titanium tetraisopropoxide, zirconium n-propoxide, and aluminum isopropoxide; the silicate compound includes one or more of methyl orthosilicate, ethyl orthosilicate, and polyethyl silicate; And / or, the catalyst includes one or a combination of multiple of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, ammonia water, sodium hydroxide, ethylenediamine, and hexamethylenediamine.

5. The preparation method according to claim 4, characterized in that: The alcohol includes one or more of methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, butanediol, and the alcohol ether includes one or more of ethylene glycol monomethyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether. And / or, in the mixed solvent, the mass ratio of water to organic solvent is 10-25:5-15; And / or, in the mixed reaction system, the mass ratio of the metal alkoxide compound and / or silicate compound, the organic solvent, and the silica aerogel is 2-5:3-15:1; And / or, in the mixed reaction system, the mass ratio of water, organic solvent and catalyst is 10-25:5-15:1-3.

6. The preparation method according to claim 3, characterized in that: The temperature of the sol-gel reaction is 20-50° C., and / or the time of the sol-gel reaction is 1-2 hours, and / or the drying is spray drying.

7. The inorganic-coated silica aerogel composite material obtained according to the preparation method according to any one of claims 3 to 6.

8. Use of the inorganic-coated silica aerogel composite material according to any one of claims 1, 2, and 7 in the preparation of water-based coatings, wherein the coating formed by the water-based coating has at least a thermal insulation function.

9. A water-based thermal insulation coating, characterized in that: A silica aerogel composite material comprising an inorganic substance coated as described in any one of claims 1, 2 and 7; Preferably, the content of the inorganic-coated silica aerogel composite material is greater than 10%, more preferably greater than 20%.

10. A thermal insulation coating, characterized in that: The thermal insulation coating is formed by the water-based thermal insulation coating according to claim 9.

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