Silicon-titanium aerogel, silicon-titanium aerogel modified silane emulsion, preparation method of silicon-titanium aerogel modified silane emulsion and super-hydrophobic self-cleaning hydraulic lime mortar

Abstract

The invention belongs to the technical field of lime mortar, and provides silicon-titanium aerogel, silicon-titanium aerogel modified silane emulsion, a preparation method of the silicon-titanium aerogel modified silane emulsion and super-hydrophobic self-cleaning hydraulic lime mortar. The preparation method of the silicon-titanium aerogel comprises the following steps: mixing silicon dioxide sol and titanium dioxide sol to obtain silicon-titanium co-sol, and sequentially standing and aging the silicon-titanium co-sol to obtain gel; and carrying out supercritical carbon dioxide drying on the gel to obtain the dried silicon-titanium aerogel. The physical and chemical properties of the surface of the lime mortar are changed through silicon dioxide and surface chemical modification (such as silane and the like), so that the lime mortar has super-hydrophobic and self-cleaning characteristics; the traditional advantages of lime mortar, such as air permeability and environmental friendliness, are maintained, and meanwhile, the water resistance and the pollution resistance of the mortar are also greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of lime mortar, and in particular to a silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion and a preparation method thereof, and a super-hydrophobic self-cleaning hydraulic lime mortar. Background Art

[0002] Natural hydraulic lime mortar has a long history of application as a building plastering material, especially in the restoration and protection of historical buildings. Traditional lime mortar has good air permeability, plasticity and adhesion, which makes it a natural and environmentally friendly material suitable for the decoration and protection of building walls. Another advantage of lime mortar is that it has good self-healing ability. When microcracks appear, lime mortar can absorb carbon dioxide in the air and react with water to generate calcium carbonate, thereby filling the cracks and enhancing the durability of the building. However, traditional natural hydraulic lime mortar also has some disadvantages, especially in modern building applications. Its main problem is poor water resistance and easy erosion by rain, which causes the mortar to gradually weather and peel off, especially in humid environments. In addition, due to its rough surface and easy water absorption, dirt and pollutants are easily attached to the mortar surface, resulting in poor appearance and frequent cleaning and maintenance. Therefore, in the process of modern and historical building restoration, how to improve the water resistance and self-cleaning ability of traditional lime mortar has become a technical problem that needs to be solved urgently.

[0003] In order to overcome the shortcomings of traditional natural hydraulic lime mortar, super-hydrophobic self-cleaning natural hydraulic lime mortar plastering materials have become a research hotspot in the current field of building materials. Super-hydrophobic technology forms a nano-level rough structure and low surface energy chemical modification on the surface of lime mortar, so that its surface can effectively repel water droplets and achieve a super-hydrophobic effect. The water contact angle of the super-hydrophobic surface is generally more than 150 degrees, and water droplets can roll on the surface like a ball, taking away dust and dirt. This is the so-called "self-cleaning" effect. Such characteristics greatly reduce the erosion and pollution of rainwater and pollutants on the mortar surface, extending the service life of the building.

[0004] Another important advantage of super-hydrophobic self-cleaning lime mortar is that it maintains the traditional advantages of lime mortar, such as air permeability and environmental friendliness, while greatly improving the waterproofness and stain resistance of the mortar. This composite functional material can be used in modern buildings and is particularly suitable for the restoration and protection of historical buildings. By combining nanotechnology with lime mortar, it is given new functionality, which can not only reduce maintenance costs and extend the life of the building, but also improve the appearance quality of the building, keeping it clean and tidy for a long time. The application background of super-hydrophobic self-cleaning natural hydraulic lime mortar is mainly concentrated in two aspects: exterior wall coating of modern buildings and protection and restoration of historical buildings. With the acceleration of urbanization and the improvement of environmental protection requirements, the durability and low maintenance cost of building materials have become the focus of the construction industry. Although traditional lime mortar has excellent environmental performance, its susceptibility to water erosion and surface pollution limits its wide application. The emergence of super-hydrophobic self-cleaning lime mortar provides a new type of material with low maintenance cost and strong durability for buildings, which retains the natural texture and ecological characteristics of lime mortar while meeting functional requirements.

[0005] In the restoration of historical buildings, how to improve the protective ability of the original building materials without changing their characteristics is a major technical challenge. The air permeability and self-healing ability of superhydrophobic self-cleaning lime mortar make it an ideal restoration material. At the same time, the superhydrophobic function can effectively prevent moisture from eroding the building structure. Through this new material, historical buildings can be better protected without destroying their original appearance, slowing down the process of weathering and aging.

[0006] Therefore, the research obtains a silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion and its preparation method and a super-hydrophobic self-cleaning hydraulic lime mortar, which not only retains the original excellent properties of the lime mortar, but also improves its hydrophobic self-cleaning ability, which is of great significance. Summary of the invention

[0007] The purpose of the present invention is to provide a silicon-titanium aerogel, a silicon-titanium aerogel-modified silane emulsion and a preparation method thereof, and a super-hydrophobic self-cleaning hydraulic lime mortar in view of the shortcomings of lime mortar plastering in the prior art.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing silicon-titanium aerogel, comprising the following steps:

[0010] 1) mixing a silicon source and anhydrous ethanol to obtain a silicon solution, and adding water droplets to the silicon solution to form a silica sol;

[0011] A titanium source and anhydrous ethanol are mixed to obtain a titanium solution, and water is added dropwise to the titanium solution to form a titanium dioxide sol;

[0012] 2) mixing the silica sol and the titania sol to obtain a silica-titanium co-sol, and the silica-titanium co-sol is allowed to stand and aged in sequence to obtain a gel;

[0013] 3) The gel is dried with supercritical carbon dioxide to obtain dry silicon-titanium aerogel.

[0014] Preferably, the silicon source comprises one or more of ethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, propyltrimethoxysilane and colloidal silica; the titanium source comprises one or more of tetrabutyl titanate, tetraisopropyl titanate and titanium isopropoxide;

[0015] In the silica sol, the mass ratio of the silicon source, anhydrous ethanol and water is 10-15:30-45:20-50, and the dropping rate is 1-2 mL / min; in the titanium dioxide sol, the mass ratio of the titanium source, anhydrous ethanol and water is 10-20:30-60:30-50, and the dropping rate is 0.5-1 mL / min.

[0016] Preferably, in step 2), the mass ratio of the silica sol to the titanium dioxide sol is 10-15:10-20, and the standing time is 6-12 hours;

[0017] The aging is carried out in an aging solution, which contains one or more of anhydrous ethanol, methanol, isopropanol and propanol; the aging temperature is 20 to 60° C., and the aging time is 12 to 36 hours.

[0018] Preferably, in the supercritical carbon dioxide drying in step 3), the system pressure is first controlled to be greater than 7.38 MPa and the system temperature is less than 31.1°C to keep the carbon dioxide in liquid state; then the temperature is increased and the pressure is decreased in sequence, the pressure remains unchanged during the temperature increase, and the target temperature of the temperature increase is greater than 31.1°C.

[0019] The invention also provides silicon-titanium aerogel prepared by the preparation method.

[0020] The present invention also provides a method for preparing a silicon-titanium aerogel-modified silane emulsion from the silicon-titanium aerogel, comprising the following steps:

[0021] (1) ultrasonically dispersing the silicon-titanium aerogel in water to obtain a silicon-titanium aerogel dispersion;

[0022] Add the silane solution dropwise into the emulsifier aqueous solution and stir to form a silane emulsion;

[0023] (2) The titanium-silicon aerogel dispersion is added dropwise to the silane emulsion for reaction to obtain the titanium-silicon aerogel modified silane emulsion.

[0024] Preferably, the mass ratio of silicon titanium aerogel to water is 5-10:10-15; the silane solution is obtained by mixing a silane coupling agent and water, and the mass ratio of the silane coupling agent to water is 30-40:20-40; the emulsifier aqueous solution is obtained by dissolving the emulsifier in water, and the mass ratio of the emulsifier to water is 2-5:10-15;

[0025] The mass ratio of silicon-titanium aerogel, silane coupling agent and emulsifier is 5-10:30-40:2-5;

[0026] The silane coupling agent is one or more of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, vinyl triisopropoxy silane, 1,4-butylene glycol methacrylate and polydimethylsiloxane;

[0027] The emulsifier is one or more of Tween-80, sodium lauryl sulfate, fatty alcohol polyoxyethylene ether and hexadecyl trimethyl ammonium chloride.

[0028] Preferably, the power of the ultrasonic dispersion in step (1) is 150-300 kW, and the ultrasonic dispersion time is 0.5-1 h; the dropwise addition rate is 0.5-1.5 mL / min, and the stirring rate is 300-600 rpm;

[0029] The dropping rate of step (2) is 1-2 mL / min, the reaction temperature is 30-50° C., the reaction time is 1-3 h, and the stirring rate during the reaction is 400-600 rpm.

[0030] The invention also provides a silicon-titanium aerogel modified silane emulsion prepared by the method.

[0031] The present invention also provides a super-hydrophobic self-cleaning hydraulic lime mortar comprising the silicon-titanium aerogel modified silane emulsion, wherein the super-hydrophobic self-cleaning hydraulic lime mortar comprises the following components in parts by weight: 40 to 50 parts of natural hydraulic lime, 40 to 100 parts of fine aggregate, 3 to 10 parts of silicon-titanium aerogel modified silane emulsion, 1 to 3 parts of nano-silicon dioxide, 0.5 to 2 parts of a water reducer, 0.1 to 1 part of a dispersant, and 20 to 30 parts of water.

[0032] The beneficial effects of the present invention include the following:

[0033] The present invention improves the functionality of traditional lime mortar and endows it with super-hydrophobic and self-cleaning properties; the physical and chemical properties of the surface of the lime mortar are changed by silicon dioxide and surface chemical modification (such as silane, etc.), so that it has super-hydrophobic and self-cleaning properties; the super-hydrophobic and self-cleaning hydraulic lime mortar of the present invention not only retains the traditional advantages of lime mortar, such as air permeability and environmental friendliness, but also greatly improves the waterproofness and stain resistance of the mortar. DETAILED DESCRIPTION

[0034] The present invention provides a method for preparing silicon-titanium aerogel, comprising the following steps:

[0035] 1) mixing a silicon source and anhydrous ethanol to obtain a silicon solution, and adding water droplets to the silicon solution to form a silica sol;

[0036] A titanium source and anhydrous ethanol are mixed to obtain a titanium solution, and water is added dropwise to the titanium solution to form a titanium dioxide sol;

[0037] 2) mixing the silica sol and the titania sol to obtain a silica-titanium co-sol, and the silica-titanium co-sol is allowed to stand and aged in sequence to obtain a gel;

[0038] 3) The gel is dried with supercritical carbon dioxide to obtain dry silicon-titanium aerogel.

[0039] In the present invention, the silicon source preferably comprises one or more of ethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, propyltrimethoxysilane and colloidal silica; the titanium source preferably comprises one or more of tetrabutyl titanate, tetraisopropyl titanate and titanium isopropoxide;

[0040] In the silica sol, the mass ratio of the silicon source, anhydrous ethanol and water is preferably 10-15:30-45:20-50, more preferably 11-14:35-40:25-45, and more preferably 12-13:36-37:30-40; the dripping rate is preferably 1-2 mL / min, more preferably 1.2-1.8 mL / min, and more preferably 1.5-1.6 mL / min; in the titanium dioxide sol, the mass ratio of the titanium source, anhydrous ethanol and water is preferably 10-20:30-60:30-50, more preferably 12-18:35-55:35-45, and more preferably 15-16:40-50:38-40, and the dripping rate is preferably 0.5-1 mL / min, more preferably 0.6-0.9 mL / min, and more preferably 0.7-0.8 mL / min.

[0041] When water is added to the silicon solution, the silicon source undergoes hydrolysis and polycondensation to form silicon dioxide sol; when water is added to the titanium solution, the titanium source is hydrolyzed to form titanium dioxide sol, and the water is added slowly to prevent precipitation caused by excessive reaction.

[0042] In the present invention, the mass ratio of the silica sol to the titanium dioxide sol in step 2) is preferably 10-15:10-20, more preferably 11-14:12-18, more preferably 12-13:15-16, and the standing time is preferably 6-12h, more preferably 8-11h, more preferably 9-10h;

[0043] The aging is carried out in an aging solution, which preferably contains one or more of anhydrous ethanol, methanol, isopropanol and propanol; the aging temperature is preferably 20-60°C, more preferably 30-50°C, more preferably 40°C, and the aging time is preferably 12-36h, more preferably 18-30h, more preferably 22-25h.

[0044] In the present invention, during the mixing process of the silica sol and the titania sol in step 2), the silica sol and the titania sol are stirred evenly to make the silica sol and the titania sol evenly dispersed and the silicon and titanium substances fully mixed; during the standing process, a polycondensation reaction occurs spontaneously to form a three-dimensional network structure, which is gradually transformed into a gel.

[0045] In the present invention, in the supercritical carbon dioxide drying in step 3), the system pressure is first controlled to be greater than 7.38MPa and the system temperature is less than 31.1°C to keep the carbon dioxide in a liquid state; then the temperature is increased and the pressure is decreased in sequence, the pressure remains unchanged during the temperature increase, and the target temperature of the temperature increase is greater than 31.1°C.

[0046] In the present invention, supercritical carbon dioxide drying is carried out in a supercritical drying kettle, liquid carbon dioxide is slowly introduced into the supercritical drying kettle, and the system pressure of the drying kettle is gradually increased to a level higher than the critical pressure of carbon dioxide (7.38MPa). At the same time, the system temperature is kept lower than the critical temperature of carbon dioxide (31.1°C) to keep the carbon dioxide in a liquid state; then, while keeping the pressure constant, the temperature is gradually increased to exceed the critical temperature of carbon dioxide (31.1°C). During the heating process, the carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface, thereby avoiding the action of capillary force; then, the temperature and pressure are kept in the supercritical region, the pressure is slowly reduced, and the supercritical carbon dioxide is slowly released through the exhaust port. During this process, the carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure; when the carbon dioxide in the system is completely released, the temperature is gradually reduced, the drying kettle is opened, and the dried silicon-titanium aerogel is taken out.

[0047] The invention also provides silicon-titanium aerogel prepared by the preparation method.

[0048] The present invention also provides a method for preparing a silicon-titanium aerogel-modified silane emulsion from the silicon-titanium aerogel, comprising the following steps:

[0049] (1) ultrasonically dispersing the silicon-titanium aerogel in water to obtain a silicon-titanium aerogel dispersion;

[0050] Add the silane solution dropwise into the emulsifier aqueous solution and stir to form a silane emulsion;

[0051] (2) The titanium-silicon aerogel dispersion is added dropwise to the silane emulsion for reaction to obtain the titanium-silicon aerogel modified silane emulsion.

[0052] In the present invention, the mass ratio of silicon titanium aerogel to water is preferably 5-10:10-15, more preferably 6-9:11-14, more preferably 7-8:12-13; the silane solution is obtained by mixing a silane coupling agent and water, and the mass ratio of the silane coupling agent to water is preferably 30-40:20-40, more preferably 32-38:25-35, and more preferably 35-36:30; the emulsifier aqueous solution is an emulsifier dissolved in water, and the mass ratio of the emulsifier to water is preferably 2-5:10-15, more preferably 3-4:11-14, and more preferably 3.5:12-13;

[0053] The mass ratio of silicon-titanium aerogel, silane coupling agent and emulsifier is preferably 5-10:30-40:2-5, more preferably 6-9:32-38:3-4, and more preferably 7-8:35-36:3.5;

[0054] The silane coupling agent is preferably one or more of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, vinyl triisopropoxy silane, 1,4-butylene glycol methacrylate and polydimethylsiloxane;

[0055] The emulsifier is preferably one or more of Tween-80, sodium lauryl sulfate, fatty alcohol polyoxyethylene ether and hexadecyl trimethyl ammonium chloride.

[0056] In the present invention, the power of the ultrasonic dispersion in step (1) is preferably 150-300 kW, more preferably 200-250 kW, and the ultrasonic dispersion time is preferably 0.5-1 h; the dropwise addition rate is preferably 0.5-1.5 mL / min, more preferably 0.8-1.2 mL / min, more preferably 1 mL / min, and the stirring rate is preferably 300-600 rpm, more preferably 350-550 rpm, more preferably 400-500 rpm;

[0057] The dropping rate of step (2) is preferably 1-2 mL / min, more preferably 1.2-1.8 mL / min, more preferably 1.5-1.6 mL / min, the reaction temperature is preferably 30-50°C, more preferably 35-45°C, more preferably 40°C; the reaction time is preferably 1-3 h, more preferably 1.5-2.5 h, more preferably 2 h, and the stirring rate during the reaction is preferably 400-600 rpm, more preferably 450-550 rpm, more preferably 500 rpm.

[0058] In the present invention, ultrasonic dispersion is used to ensure that the aerogel particles are uniformly dispersed in water, and the aerogel particles are completely dispersed and not agglomerated; the silane emulsion is a uniform white or microemulsion silane emulsion.

[0059] In the present invention, stirring is performed during the dropping process in step (2) to ensure that the aerogel is evenly dispersed in the silane emulsion and reacts with the silane.

[0060] The invention also provides a silicon-titanium aerogel modified silane emulsion prepared by the method.

[0061] The present invention also provides a super-hydrophobic self-cleaning hydraulic lime mortar comprising the silicon-titanium aerogel modified silane emulsion, wherein the super-hydrophobic self-cleaning hydraulic lime mortar comprises the following components in parts by weight: 40 to 50 parts of natural hydraulic lime, 40 to 100 parts of fine aggregate, 3 to 10 parts of silicon-titanium aerogel modified silane emulsion, 1 to 3 parts of nano-silicon dioxide, 0.5 to 2 parts of a water reducer, 0.1 to 1 part of a dispersant, and 20 to 30 parts of water.

[0062] In the super-hydrophobic self-cleaning hydraulic lime mortar of the present invention, natural hydraulic lime is preferably 42 to 48 parts, more preferably 44 to 46 parts, and more preferably 45 parts; fine aggregate is preferably 50 to 90 parts, more preferably 60 to 80 parts, and more preferably 70 parts; silicon-titanium aerogel-modified silane emulsion is preferably 4 to 8 parts, more preferably 5 to 7 parts, and more preferably 6 parts; nano-silicon dioxide is preferably 1.5 to 2.5 parts, and more preferably 2 parts; water reducer is preferably 0.8 to 1.6 parts, more preferably 1 to 1.5 parts, and more preferably 1.2 parts; dispersant is preferably 0.3 to 0.8 parts, and more preferably 0.5 to 0.6 parts; water is preferably 22 to 28 parts, more preferably 24 to 26 parts, and more preferably 25 parts.

[0063] In the present invention, the fine aggregate is preferably fine sand with a particle size of 0.1 to 0.3 mm; the water reducer is preferably a polycarboxylic acid high-efficiency water reducer or a naphthalene-based water reducer; and the dispersant is preferably hydroxyethyl cellulose ether and / or anionic cellulose ether.

[0064] In the present invention, the method for preparing super-hydrophobic self-cleaning hydraulic lime mortar is preferably as follows: natural hydraulic lime, nano-silicon dioxide and water are first mixed, the first mixture and fine aggregate are second mixed, and the second mixture, silicon-titanium aerogel-modified silane emulsion, water reducing agent and dispersant are third mixed to obtain super-hydrophobic self-cleaning natural hydraulic lime mortar;

[0065] The first mixing rate is preferably 270-300 rpm, more preferably 280-290 rpm, more preferably 285 rpm, and the first mixing time is preferably 4-6 min, more preferably 5 min; the second mixing rate is preferably 130-150 rpm, more preferably 135-145 rpm, more preferably 140 rpm, and the second mixing time is preferably 4-6 min, more preferably 5 min; the third mixing rate is preferably 270-300 rpm, more preferably 280-290 rpm, more preferably 285 rpm, and the third mixing time is preferably 15-20 min, more preferably 17-18 min.

[0066] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0067] Natural hydraulic lime NHL5 produced by StAstier, France, has an apparent density of 0.85 g / cm 3 The 28-day compressive strength is 8MPa, which meets the standard requirements of European standard EN459-12010; the fine aggregate is fine sand with a particle size of 0.1 to 0.3mm; the water reducer is naphthalene-based water reducer FDN-C, and the dispersant is hydroxyethyl cellulose ether MH300P2;

[0068] In the embodiments, the numbers are all mass numbers; in the preparation of silicon-titanium aerogel, the stirring rate is 300 rpm, and in the preparation of silicon-titanium aerogel-modified silane emulsion, the stirring rate is 500 rpm; in the preparation of superhydrophobic self-cleaning hydraulic lime mortar, the low-speed stirring rate is 140 rpm, and the high-speed stirring rate is 285 rpm.

[0069] Example 1

[0070] The preparation method of silicon titanium aerogel is as follows:

[0071] 10 parts of tetraethyl orthosilicate and 30 parts of anhydrous ethanol were stirred evenly to obtain a silicon solution; 20 parts of deionized water were added to the silicon solution at a rate of 1.5 mL / min, and the tetraethyl orthosilicate was hydrolyzed and polycondensed to form a silica sol. 10 parts of tetrabutyl titanate were added to 35 parts of anhydrous ethanol and stirred evenly to obtain a titanium solution. Under stirring conditions, 30 parts of deionized water were added at a rate of 0.8 mL / min to hydrolyze the tetrabutyl titanate to form a titanium dioxide sol.

[0072] 10 parts of silica sol and 12 parts of titanium dioxide sol were mixed and stirred evenly to obtain a silicon-titanium co-sol. The silicon-titanium co-sol was allowed to stand for 6 hours to allow it to undergo a spontaneous polycondensation reaction to form a three-dimensional network structure and gradually transform into a silicon-titanium gel. The silicon-titanium gel was placed in anhydrous ethanol at 30°C for aging for 12 hours.

[0073] After aging, the washed silica-titanium gel is carefully placed in a supercritical drying kettle, and liquid carbon dioxide is slowly introduced into the drying kettle, gradually increasing the pressure to a level higher than the critical pressure of carbon dioxide, 7.38 MPa. At the same time, the system temperature is kept below the critical temperature of carbon dioxide, 31.1°C, to keep the carbon dioxide in a liquid state. While keeping the pressure constant, the temperature is gradually increased to a level higher than the critical temperature of carbon dioxide, 31.1°C. In this process, carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the action of capillary forces. Keep the temperature and pressure in the supercritical region, and then slowly reduce the pressure so that the supercritical carbon dioxide is slowly released through the exhaust port. In this process, carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure. When the carbon dioxide in the system is completely released, the temperature is gradually reduced to obtain a dried silica-titanium aerogel.

[0074] The preparation method of silicon-titanium aerogel modified silane emulsion is:

[0075] 5 parts of silicon-titanium aerogel powder were added to 10 parts of deionized water, and ultrasonically dispersed at a power of 200 kW for 0.5 h to ensure that the aerogel particles were evenly dispersed in the water without agglomeration, thereby obtaining a silicon-titanium aerogel dispersion.

[0076] 30 parts of silane coupling agent (trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate and 1,4-butylene glycol methacrylate in a mass ratio of 1:1:1) were added to 20 parts of water and stirred to form a homogeneous silane solution. 2 parts of Tween-80 were dissolved in 10 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 1 mL / min and stirred continuously to form a uniform silane emulsion.

[0077] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min, stirring while adding, and the reaction was stirred at 40° C. for 1.5 h to ensure that the aerogel was evenly dispersed in the emulsion and reacted with the silane to obtain a silicon-titanium aerogel modified silane emulsion.

[0078] The preparation method of super hydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0079] Add 40 parts of natural hydraulic lime, 1 part of nano-silicon dioxide and 20 parts of water into a mortar mixer and stir at high speed for 5 minutes; slowly add 60 parts of fine aggregate into the mortar mixer and stir at low speed for 5 minutes, then add 4 parts of silicon-titanium aerogel modified silane emulsion, 1 part of water reducer and 0.5 part of dispersant, and stir at high speed for 17 minutes to obtain a super-hydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0080] Example 2

[0081] The preparation method of silicon titanium aerogel is as follows:

[0082] 10 parts of methyl orthosilicate and 35 parts of anhydrous ethanol were stirred evenly to obtain a silicon solution; 20 parts of deionized water were added to the silicon solution at a rate of 1.2 mL / min, and the methyl orthosilicate was hydrolyzed and polycondensed to form a silica sol. 10 parts of tetraisopropyl titanate were added to 30 parts of anhydrous ethanol and stirred evenly to obtain a titanium solution. Under stirring conditions, 30 parts of deionized water were added at a rate of 0.6 mL / min to hydrolyze the tetraisopropyl titanate to form a titanium dioxide sol.

[0083] 10 parts of silica sol and 12 parts of titanium dioxide sol were mixed and stirred evenly to obtain a silicon-titanium co-sol. The silicon-titanium co-sol was allowed to stand for 6 hours to allow it to undergo a spontaneous polycondensation reaction to form a three-dimensional network structure and gradually transform into a silicon-titanium gel. The silicon-titanium gel was placed in anhydrous ethanol at 30°C for aging for 12 hours.

[0084] After aging, the washed silica-titanium gel is carefully placed in a supercritical drying kettle, and liquid carbon dioxide is slowly introduced into the drying kettle, gradually increasing the pressure to a level higher than the critical pressure of carbon dioxide, 7.38 MPa. At the same time, the system temperature is kept below the critical temperature of carbon dioxide, 31.1°C, to keep the carbon dioxide in a liquid state. While keeping the pressure constant, the temperature is gradually increased to a level higher than the critical temperature of carbon dioxide, 31.1°C. In this process, carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the action of capillary forces. Keep the temperature and pressure in the supercritical region, and then slowly reduce the pressure so that the supercritical carbon dioxide is slowly released through the exhaust port. In this process, carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure. When the carbon dioxide in the system is completely released, the temperature is gradually reduced to obtain a dried silica-titanium aerogel.

[0085] The preparation method of silicon-titanium aerogel modified silane emulsion is:

[0086] 5 parts of silicon-titanium aerogel powder were added to 12 parts of deionized water, and ultrasonically dispersed at a power of 180 kW for 0.5 h to ensure that the aerogel particles were evenly dispersed in the water without agglomeration, thereby obtaining a silicon-titanium aerogel dispersion.

[0087] 30 parts of silane coupling agent (trimethylolpropane trimethacrylate) were added to 25 parts of water and stirred to form a homogeneous silane solution. 2 parts of sodium dodecyl sulfate were dissolved in 10 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 0.8 mL / min and stirred continuously to form a uniform silane emulsion.

[0088] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.2 mL / min, stirring while adding, and the reaction was stirred at 40° C. for 1.5 h to ensure that the aerogel was evenly dispersed in the emulsion and reacted with the silane to obtain a silicon-titanium aerogel modified silane emulsion.

[0089] The preparation method of super hydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0090] Add 40 parts of natural hydraulic lime, 2 parts of nano-silicon dioxide and 20 parts of water into a mortar mixer and stir at high speed for 4 minutes; slowly add 60 parts of fine aggregate into the mortar mixer and stir at low speed for 4 minutes, then add 4 parts of silicon-titanium aerogel modified silane emulsion, 1.5 parts of water reducer and 0.6 parts of dispersant, and stir at high speed for 15 minutes to obtain a super-hydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0091] Example 3

[0092] The preparation method of silicon titanium aerogel is as follows:

[0093] 12 parts of methyltriethoxysilane and 30 parts of anhydrous ethanol were stirred evenly to obtain a silicon solution; 25 parts of deionized water were added to the silicon solution at a rate of 1.8 mL / min, and methyltriethoxysilane was hydrolyzed and polycondensed to form a silica sol. 12 parts of titanium isopropoxide were added to 40 parts of anhydrous ethanol and stirred evenly to obtain a titanium solution. Under stirring conditions, 40 parts of deionized water were added at a rate of 1 mL / min to hydrolyze the titanium isopropoxide to form a titanium dioxide sol.

[0094] 12 parts of silica sol and 12 parts of titanium dioxide sol were mixed and stirred evenly to obtain a silicon-titanium co-sol. The silicon-titanium co-sol was allowed to stand for 8 hours to allow it to undergo a spontaneous polycondensation reaction to form a three-dimensional network structure and gradually transform into a silicon-titanium gel. The silicon-titanium gel was placed in anhydrous ethanol at 40°C for aging for 12 hours.

[0095] After aging, the washed silica-titanium gel is carefully placed in a supercritical drying kettle, and liquid carbon dioxide is slowly introduced into the drying kettle, gradually increasing the pressure to a level higher than the critical pressure of carbon dioxide, 7.38 MPa. At the same time, the system temperature is kept below the critical temperature of carbon dioxide, 31.1°C, to keep the carbon dioxide in a liquid state. While keeping the pressure constant, the temperature is gradually increased to a level higher than the critical temperature of carbon dioxide, 31.1°C. In this process, carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the action of capillary forces. Keep the temperature and pressure in the supercritical region, and then slowly reduce the pressure so that the supercritical carbon dioxide is slowly released through the exhaust port. In this process, carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure. When the carbon dioxide in the system is completely released, the temperature is gradually reduced to obtain a dried silica-titanium aerogel.

[0096] The preparation method of silicon-titanium aerogel modified silane emulsion is:

[0097] 8 parts of silicon-titanium aerogel powder were added to 15 parts of deionized water, and ultrasonically dispersed at a power of 300 kW for 0.5 h to ensure that the aerogel particles were evenly dispersed in the water without agglomeration, thereby obtaining a silicon-titanium aerogel dispersion.

[0098] 40 parts of silane coupling agent (ethylene glycol dimethacrylate) were added to 30 parts of water and stirred to form a homogeneous silane solution. 4 parts of hexadecyltrimethylammonium chloride were dissolved in 12 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 1.5 mL / min and stirred continuously to form a uniform silane emulsion.

[0099] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 2 mL / min, stirring while adding, and the reaction was stirred at 40°C for 2 h to ensure that the aerogel was evenly dispersed in the emulsion and reacted with the silane to obtain a silicon-titanium aerogel modified silane emulsion.

[0100] The preparation method of super hydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0101] Add 40 parts of natural hydraulic lime, 3 parts of nano-silicon dioxide and 24 parts of water into a mortar mixer and stir at high speed for 6 minutes; slowly add 80 parts of fine aggregate into the mortar mixer and stir at low speed for 6 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 1.5 parts of water reducer and 1 part of dispersant, and stir at high speed for 20 minutes to obtain a super-hydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0102] Example 4

[0103] The preparation method of silicon titanium aerogel is as follows:

[0104] 12 parts of propyltrimethoxysilane and 35 parts of anhydrous ethanol were stirred evenly to obtain a silicon solution; 40 parts of deionized water were added to the silicon solution at a rate of 1.5 mL / min, and propyltrimethoxysilane was hydrolyzed and polycondensed to form a silica sol. 15 parts of tetrabutyl titanate were added to 45 parts of anhydrous ethanol and stirred evenly to obtain a titanium solution. Under stirring conditions, 40 parts of deionized water were added at a rate of 0.8 mL / min to hydrolyze the tetrabutyl titanate to form a titanium dioxide sol.

[0105] 15 parts of silica sol and 10 parts of titanium dioxide sol were mixed and stirred evenly to obtain a silicon-titanium co-sol. The silicon-titanium co-sol was allowed to stand for 6 hours to allow it to undergo a spontaneous polycondensation reaction to form a three-dimensional network structure and gradually transform into a silicon-titanium gel. The silicon-titanium gel was placed in anhydrous ethanol at 45°C for aging for 12 hours.

[0106] After aging, the washed silica-titanium gel is carefully placed in a supercritical drying kettle, and liquid carbon dioxide is slowly introduced into the drying kettle, gradually increasing the pressure to a level higher than the critical pressure of carbon dioxide, 7.38 MPa. At the same time, the system temperature is kept below the critical temperature of carbon dioxide, 31.1°C, to keep the carbon dioxide in a liquid state. While keeping the pressure constant, the temperature is gradually increased to a level higher than the critical temperature of carbon dioxide, 31.1°C. In this process, carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the action of capillary forces. Keep the temperature and pressure in the supercritical region, and then slowly reduce the pressure so that the supercritical carbon dioxide is slowly released through the exhaust port. In this process, carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure. When the carbon dioxide in the system is completely released, the temperature is gradually reduced to obtain a dried silica-titanium aerogel.

[0107] The preparation method of silicon-titanium aerogel modified silane emulsion is:

[0108] 8 parts of silicon-titanium aerogel powder were added to 15 parts of deionized water, and ultrasonically dispersed at a power of 200 kW for 0.5 h to ensure that the aerogel particles were evenly dispersed in the water without agglomeration, to obtain a silicon-titanium aerogel dispersion.

[0109] 40 parts of silane coupling agent (vinyl triisopropoxy silane) were added to 40 parts of water and stirred to form a homogeneous silane solution. 4 parts of Tween-80 were dissolved in 12 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 1 mL / min and stirred continuously to form a uniform silane emulsion.

[0110] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min, stirring while adding, and the reaction was stirred at 40° C. for 2 h to ensure that the aerogel was evenly dispersed in the emulsion and reacted with the silane to obtain a silicon-titanium aerogel modified silane emulsion.

[0111] The preparation method of super hydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0112] Add 40 parts of natural hydraulic lime, 3 parts of nano-silicon dioxide and 20 parts of water into a mortar mixer and stir at high speed for 5 minutes; slowly add 40 parts of fine aggregate into the mortar mixer and stir at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water reducer and 1 part of dispersant, and stir at high speed for 17 minutes to obtain a super-hydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0113] Example 5

[0114] The preparation method of silicon titanium aerogel is as follows:

[0115] 12 parts of colloidal silica and 36 parts of anhydrous ethanol were stirred evenly to obtain a silicon solution; 40 parts of deionized water were added to the silicon solution at a rate of 1.7 mL / min, and the colloidal silica was hydrolyzed and polycondensed to form a silica sol. 15 parts of tetraisopropyl titanate were added to 50 parts of anhydrous ethanol and stirred evenly to obtain a titanium solution. Under stirring conditions, 40 parts of deionized water were added at a rate of 0.7 mL / min to hydrolyze the tetraisopropyl titanate to form a titanium dioxide sol.

[0116] 12 parts of silica sol and 15 parts of titanium dioxide sol were mixed and stirred evenly to obtain a silicon-titanium co-sol. The silicon-titanium co-sol was allowed to stand for 6 hours to allow it to undergo a spontaneous polycondensation reaction to form a three-dimensional network structure and gradually transform into a silicon-titanium gel. The silicon-titanium gel was placed in anhydrous ethanol at 40°C for aging for 24 hours.

[0117] After aging, the washed silica-titanium gel is carefully placed in a supercritical drying kettle, and liquid carbon dioxide is slowly introduced into the drying kettle, gradually increasing the pressure to a level higher than the critical pressure of carbon dioxide, 7.38 MPa. At the same time, the system temperature is kept below the critical temperature of carbon dioxide, 31.1°C, to keep the carbon dioxide in a liquid state. While keeping the pressure constant, the temperature is gradually increased to a level higher than the critical temperature of carbon dioxide, 31.1°C. In this process, carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the action of capillary forces. Keep the temperature and pressure in the supercritical region, and then slowly reduce the pressure so that the supercritical carbon dioxide is slowly released through the exhaust port. In this process, carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure. When the carbon dioxide in the system is completely released, the temperature is gradually reduced to obtain a dried silica-titanium aerogel.

[0118] The preparation method of silicon-titanium aerogel modified silane emulsion is:

[0119] 10 parts of silicon-titanium aerogel powder were added to 12 parts of deionized water, and ultrasonically dispersed at a power of 250 kW for 1 hour to ensure that the aerogel particles were evenly dispersed in the water without agglomeration, thereby obtaining a silicon-titanium aerogel dispersion.

[0120] 40 parts of silane coupling agent (vinyl triisopropoxy silane) were added to 30 parts of water and stirred to form a homogeneous silane solution. 4 parts of sodium dodecyl sulfate were dissolved in 12 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 0.8 mL / min and stirred continuously to form a uniform silane emulsion.

[0121] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.2 mL / min, stirring while adding, and the reaction was stirred at 40° C. for 2 h to ensure that the aerogel was evenly dispersed in the emulsion and reacted with the silane to obtain a silicon-titanium aerogel modified silane emulsion.

[0122] The preparation method of super hydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0123] Add 40 parts of natural hydraulic lime, 3 parts of nano-silicon dioxide and 24 parts of water into a mortar mixer and stir at high speed for 5 minutes; slowly add 40 parts of fine aggregate into the mortar mixer and stir at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water reducer and 1 part of dispersant, and stir at high speed for 16 minutes to obtain a super-hydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0124] Example 6

[0125] The preparation method of silicon titanium aerogel is as follows:

[0126] 15 parts of methyl orthosilicate and 30 parts of anhydrous ethanol were stirred evenly to obtain a silicon solution; 40 parts of deionized water were added to the silicon solution at a rate of 1.5 mL / min, and the methyl orthosilicate was hydrolyzed and polycondensed to form a silica sol. 20 parts of tetrabutyl titanate were added to 60 parts of anhydrous ethanol and stirred evenly to obtain a titanium solution. Under stirring conditions, 50 parts of deionized water were added at a rate of 0.8 mL / min to hydrolyze the tetrabutyl titanate to form a titanium dioxide sol.

[0127] 15 parts of silica sol and 20 parts of titanium dioxide sol were mixed and stirred evenly to obtain a silicon-titanium co-sol. The silicon-titanium co-sol was allowed to stand for 6 hours to allow it to undergo a spontaneous polycondensation reaction to form a three-dimensional network structure and gradually transform into a silicon-titanium gel. The silicon-titanium gel was placed in anhydrous ethanol at 40°C for aging for 24 hours.

[0128] After aging, the washed silica-titanium gel is carefully placed in a supercritical drying kettle, and liquid carbon dioxide is slowly introduced into the drying kettle, gradually increasing the pressure to a level higher than the critical pressure of carbon dioxide, 7.38 MPa. At the same time, the system temperature is kept below the critical temperature of carbon dioxide, 31.1°C, to keep the carbon dioxide in a liquid state. While keeping the pressure constant, the temperature is gradually increased to a level higher than the critical temperature of carbon dioxide, 31.1°C. In this process, carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the action of capillary forces. Keep the temperature and pressure in the supercritical region, and then slowly reduce the pressure so that the supercritical carbon dioxide is slowly released through the exhaust port. In this process, carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure. When the carbon dioxide in the system is completely released, the temperature is gradually reduced to obtain a dried silica-titanium aerogel.

[0129] The preparation method of silicon-titanium aerogel modified silane emulsion is:

[0130] 8 parts of silicon-titanium aerogel powder were added to 15 parts of deionized water, and ultrasonically dispersed at a power of 200 kW for 0.5 h to ensure that the aerogel particles were evenly dispersed in the water without agglomeration, to obtain a silicon-titanium aerogel dispersion.

[0131] 40 parts of silane coupling agent (polydimethylsiloxane) were added to 40 parts of water and stirred to form a homogeneous silane solution. 3 parts of Tween-80 were dissolved in 15 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 1 mL / min and stirred continuously to form a uniform silane emulsion.

[0132] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min, stirring while adding, and the reaction was stirred at 40° C. for 2 h to ensure that the aerogel was evenly dispersed in the emulsion and reacted with the silane to obtain a silicon-titanium aerogel modified silane emulsion.

[0133] The preparation method of super hydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0134] Add 40 parts of natural hydraulic lime, 3 parts of nano-silicon dioxide and 20 parts of water into a mortar mixer and stir at high speed for 5 minutes; slowly add 40 parts of fine aggregate into the mortar mixer and stir at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water reducer and 1 part of dispersant, and stir at high speed for 17 minutes to obtain a super-hydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0135] Example 7

[0136] The preparation method of silicon titanium aerogel is as follows:

[0137] 15 parts of tetraethyl orthosilicate and 45 parts of anhydrous ethanol were stirred evenly to obtain a silicon solution; 50 parts of deionized water were added to the silicon solution at a rate of 1.5 mL / min, and the tetraethyl orthosilicate was hydrolyzed and polycondensed to form a silica sol. 15 parts of tetrabutyl titanate were added to 45 parts of anhydrous ethanol and stirred evenly to obtain a titanium solution. Under stirring conditions, 50 parts of deionized water were added at a rate of 0.8 mL / min to hydrolyze the tetrabutyl titanate to form a titanium dioxide sol.

[0138] 15 parts of silica sol and 20 parts of titanium dioxide sol were mixed and stirred evenly to obtain a silicon-titanium co-sol. The silicon-titanium co-sol was allowed to stand for 6 hours to allow it to undergo a spontaneous polycondensation reaction to form a three-dimensional network structure and gradually transform into a silicon-titanium gel. The silicon-titanium gel was placed in anhydrous ethanol at 40°C for aging for 24 hours.

[0139] After aging, the washed silica-titanium gel is carefully placed in a supercritical drying kettle, and liquid carbon dioxide is slowly introduced into the drying kettle, gradually increasing the pressure to a level higher than the critical pressure of carbon dioxide, 7.38 MPa. At the same time, the system temperature is kept below the critical temperature of carbon dioxide, 31.1°C, to keep the carbon dioxide in a liquid state. While keeping the pressure constant, the temperature is gradually increased to a level higher than the critical temperature of carbon dioxide, 31.1°C. In this process, carbon dioxide changes from a liquid state to a supercritical state, eliminating the liquid-gas interface and thus avoiding the action of capillary forces. Keep the temperature and pressure in the supercritical region, and then slowly reduce the pressure so that the supercritical carbon dioxide is slowly released through the exhaust port. In this process, carbon dioxide directly changes from a supercritical state to a gaseous state without passing through a liquid state, thereby avoiding the collapse of the gel structure. When the carbon dioxide in the system is completely released, the temperature is gradually reduced to obtain a dried silica-titanium aerogel.

[0140] The preparation method of silicon-titanium aerogel modified silane emulsion is:

[0141] 10 parts of silicon-titanium aerogel powder were added to 15 parts of deionized water, and ultrasonically dispersed at a power of 200 kW for 0.5 h to ensure that the aerogel particles were evenly dispersed in the water without agglomeration, thereby obtaining a silicon-titanium aerogel dispersion.

[0142] 40 parts of silane coupling agent (trimethylolpropane trimethacrylate) were added to 40 parts of water and stirred to form a homogeneous silane solution. 3 parts of Tween-80 were dissolved in 12 parts of deionized water and stirred until completely dissolved to obtain an emulsifier aqueous solution. Under stirring conditions, the silane solution was added dropwise to the emulsifier aqueous solution at a rate of 1 mL / min and stirred continuously to form a uniform silane emulsion.

[0143] The silicon-titanium aerogel dispersion was added to the silane emulsion at a rate of 1.5 mL / min, stirring while adding, and the reaction was stirred at 40° C. for 1.5 h to ensure that the aerogel was evenly dispersed in the emulsion and reacted with the silane to obtain a silicon-titanium aerogel modified silane emulsion.

[0144] The preparation method of super hydrophobic self-cleaning natural hydraulic lime plastering mortar is as follows:

[0145] Add 40 parts of natural hydraulic lime, 3 parts of nano-silicon dioxide and 20 parts of water into a mortar mixer and stir at high speed for 5 minutes; slowly add 40 parts of fine aggregate into the mortar mixer and stir at low speed for 5 minutes, then add 5 parts of silicon-titanium aerogel modified silane emulsion, 2 parts of water reducer and 1 part of dispersant, and stir at high speed for 17 minutes to obtain a super-hydrophobic self-cleaning natural hydraulic lime plastering mortar.

[0146] The super-hydrophobic self-cleaning natural hydraulic lime plastering mortar of Examples 1 to 7 was subjected to performance tests, wherein the fluidity was determined according to GB / T 2419-2005 "Method for determining the fluidity of cement mortar"; the setting time was determined according to Part 8 of JGJ / T70-2009 "Test methods for basic properties of building mortar"; the compressive strength was determined according to Part 9 of JGJ / T 70-2009 "Test methods for basic properties of building mortar"; the bonding strength was determined according to Part 10 of JGJ / T 70-2009 "Test methods for basic properties of building mortar"; and the drying shrinkage was determined according to Part 12 of JGJ / T 70-2009 "Test methods for basic properties of building mortar". The test results are shown in Table 1.

[0147] Table 1 Performance test results of super hydrophobic self-cleaning natural hydraulic lime mortar in Example

[0148]

[0149] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing silicon-titanium aerogel, characterized in that: The following steps are included: 1) mixing a silicon source and anhydrous ethanol to obtain a silicon solution, and adding water droplets to the silicon solution to form a silica sol; A titanium source and anhydrous ethanol are mixed to obtain a titanium solution, and water is added dropwise to the titanium solution to form a titanium dioxide sol; 2) mixing the silica sol and the titania sol to obtain a silica-titanium co-sol, and the silica-titanium co-sol is allowed to stand and aged in sequence to obtain a gel; 3) The gel is dried with supercritical carbon dioxide to obtain dry silicon-titanium aerogel.

2. The preparation method according to claim 1, characterized in that: The silicon source comprises one or more of ethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane, propyltrimethoxysilane and colloidal silicon dioxide; the titanium source comprises one or more of tetrabutyl titanate, tetraisopropyl titanate and titanium isopropoxide; In the silica sol, the mass ratio of the silicon source, anhydrous ethanol and water is 10-15:30-45:20-50, and the dropping rate is 1-2 mL / min; in the titanium dioxide sol, the mass ratio of the titanium source, anhydrous ethanol and water is 10-20:30-60:30-50, and the dropping rate is 0.5-1 mL / min.

3. The preparation method according to claim 1 or 2, characterized in that: Step 2) the mass ratio of the silica sol to the titanium dioxide sol is 10-15:10-20, and the standing time is 6-12 hours; The aging is carried out in an aging solution, which contains one or more of anhydrous ethanol, methanol, isopropanol and propanol; the aging temperature is 20 to 60° C., and the aging time is 12 to 36 hours.

4. The preparation method according to claim 3, characterized in that: Step 3) During the supercritical carbon dioxide drying, the system pressure is first controlled to be greater than 7.38 MPa and the system temperature is less than 31.1° C. to keep the carbon dioxide in a liquid state; then the temperature is increased and the pressure is decreased in sequence, the pressure remains unchanged during the temperature increase, and the target temperature of the temperature increase is greater than 31.1° C.

5. Silicon-titanium aerogel prepared by the preparation method according to any one of claims 1 to 4.

6. The method for preparing a silicon-titanium aerogel-modified silane emulsion from a silicon-titanium aerogel according to claim 5, characterized in that: The following steps are included: (1) ultrasonically dispersing the silicon-titanium aerogel in water to obtain a silicon-titanium aerogel dispersion; Add the silane solution dropwise into the emulsifier aqueous solution and stir to form a silane emulsion; (2) The titanium-silicon aerogel dispersion is added dropwise to the silane emulsion for reaction to obtain the titanium-silicon aerogel modified silane emulsion.

7. The method according to claim 6, characterized in that The mass ratio of silicon-titanium aerogel to water is 5-10:10-15; the silane solution is obtained by mixing a silane coupling agent and water, and the mass ratio of the silane coupling agent to water is 30-40:20-40; the emulsifier aqueous solution is obtained by dissolving the emulsifier in water, and the mass ratio of the emulsifier to water is 2-5:10-15; The mass ratio of silicon-titanium aerogel, silane coupling agent and emulsifier is 5-10:30-40:2-5; The silane coupling agent is one or more of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, vinyl triisopropoxy silane, 1,4-butylene glycol methacrylate and polydimethylsiloxane; The emulsifier is one or more of Tween-80, sodium lauryl sulfate, fatty alcohol polyoxyethylene ether and hexadecyl trimethyl ammonium chloride.

8. The method according to claim 6 or 7, characterized in that: The power of the ultrasonic dispersion in step (1) is 150-300 kW, and the ultrasonic dispersion time is 0.5-1 h; the dropwise addition rate is 0.5-1.5 mL / min, and the stirring rate is 300-600 rpm; The dropping rate of step (2) is 1-2 mL / min, the reaction temperature is 30-50° C., the reaction time is 1-3 h, and the stirring rate during the reaction is 400-600 rpm.

9. The silicon-titanium aerogel modified silane emulsion prepared by the method according to any one of claims 6 to 8.

10. A super-hydrophobic self-cleaning hydraulic lime mortar comprising the silicon-titanium aerogel modified silane emulsion according to claim 9, characterized in that: The super-hydrophobic self-cleaning hydraulic lime mortar contains the following components in parts by mass: 40-50 parts of natural hydraulic lime, 40-100 parts of fine aggregate, 3-10 parts of silicon-titanium aerogel modified silane emulsion, 1-3 parts of nano-silicon dioxide, 0.5-2 parts of water reducer, 0.1-1 parts of dispersant and 20-30 parts of water.

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