Silicon dioxide aerogel slurry and preparation method thereof

Abstract

The invention provides silicon dioxide aerogel slurry and a preparation method thereof. The aerogel slurry is prepared from the following materials in parts by weight: 10 to 90 parts of water, 1 to 25 parts of hydrophobic silicon dioxide aerogel powder, 0.01 to 3 parts of an anionic surfactant, 0.01 to 0.9 part of a polymer electrolyte, 0.01 to 1 part of a suspending agent, 0.001 to 0.01 part of a pH (Potential of Hydrogen) regulator, 0.001 to 0.02 part of a de-foaming agent and 0.001 to 0.01 part of a double-layer microcapsule mildew preventive, the double-layer microcapsule mildew preventive comprises the following components in parts by weight: 1-3 parts of a mildew preventive, 1-3 parts of sodium alginate, 0.5-2 parts of calcium chloride, 5-10 parts of acetic acid, 5-10 parts of chitosan and 100-200 parts of water. The double-layer microcapsule mildew inhibitor not only exerts the mildew-proof effect of the mildew inhibitor, but also reduces the influence on the performance of aerogel slurry.

Description

Technical Field

[0001] The present application relates to the field of coating technology, and in particular to a silica aerogel slurry and a preparation method thereof. Background Art

[0002] Silica (SiO2) aerogel (hereinafter referred to as aerogel) is a porous material composed of a three-dimensional nanoparticle skeleton and nanoscale pores. It has the characteristics of low density, high porosity, high specific surface area, low thermal conductivity and strong fire resistance. It has brought new development opportunities for traditional thermal insulation materials and provided a possibility to resolve the contradiction between building energy conservation and building fire protection.

[0003] At present, in order to improve the thermal insulation performance of existing building materials, aerogel powder is usually dispersed in an aqueous system by a dispersion process to obtain aerogel slurry. However, the static stability of silica aerogel slurry obtained by the existing dispersion process or dispersion system is often difficult to ensure.

[0004] In addition, the aerogel slurry currently on the market will become moldy after being stored for a long time, which will not only affect the quality of the aerogel slurry, but also have a significant impact on the quality of aerogel-based composite building materials. If moldy aerogel-based composite building materials are put on the market, it may also endanger people's lives and health.

[0005] Therefore, there is a need for an aerogel slurry with excellent performance, stability and long-lasting preservation and a preparation method thereof. Summary of the invention

[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0007] The present application provides a silica aerogel slurry, which is prepared from the following materials, which are, by weight, 10-90 parts of water, 1-25 parts of hydrophobic silica aerogel powder, 0.01-3 parts of anionic surfactant, 0.01-0.9 parts of polymer electrolyte, 0.01-1 parts of suspending agent, 0.001-0.01 parts of pH regulator, 0.001-0.02 parts of defoaming agent and 0.001-0.01 parts of double-layer microcapsule antifungal agent, wherein the double-layer microcapsule antifungal agent comprises, by weight, 1-3 parts of antifungal agent, 1-3 parts of sodium alginate, 0.5-2 parts of calcium chloride, 5-10 parts of acetic acid, 5-10 parts of chitosan and 100-200 parts of water.

[0008] In one embodiment, the anionic surfactant is selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl polyoxyethylene ether sulfate, sodium alkyl polyoxyethylene ether carboxylate, sodium dodecyl sulfonate, sodium methylene bisnaphthalene sulfonate and sodium oleoyl methyl taurate.

[0009] In one embodiment, the anionic surfactant is sodium dodecylbenzene sulfonate (SDBS).

[0010] In one embodiment, the suspending agent is selected from one or more of hydroxypropyl methylcellulose, methylcellulose, hydroxyethyl cellulose and carboxymethyl cellulose.

[0011] In one embodiment, the suspending agent is hydroxyethyl cellulose (HEC).

[0012] In one embodiment, the polymer electrolyte is selected from one or more of sodium polyacrylate, ammonium polyacrylate, polyacrylamide, sodium polystyrene sulfonate and polystyrene-maleic anhydride copolymer.

[0013] In one embodiment, the polymer electrolyte is polyacrylamide (PAM).

[0014] In one embodiment, the polymer electrolyte has a number average molecular weight in the range of 500,000-3,000,000.

[0015] In one embodiment, the polymer electrolyte has a number average molecular weight in the range of 2,000,000-3,000,000.

[0016] In one embodiment, the defoamer is selected from one or more of BASF 2410 defoamer, Nopco 1375, Nopco 1370, Bek 024 and Digo 901W.

[0017] In one embodiment, the defoamer is a combination of Dego 901W and BASF 2410 defoamers in a weight ratio of 1:1-5.

[0018] In one embodiment, the hydrophobic silica aerogel powder has a particle size of 0.5 μm-500 μm and a bulk density of 60 kg / m 3 -120 kg / m 3 , thermal conductivity is 0.018W / m·k-0.021W / m·k and contact angle is 146°-149°.

[0019] In one embodiment, the water is distilled water or deionized water.

[0020] In one embodiment, the pH adjuster is selected from one or more of ammonia water, triethylamine, dimethylethanolamine, and 2-aminomethyl-1-propanol (AMP-95).

[0021] In one embodiment, the pH of the silica aerogel slurry is in the range of 7.5-9.5.

[0022] In one embodiment, the mildew preventer is selected from one or more of 2-octyl-4-isothiazoline-3-one (OIT), 2-butyl-1,2-benzisothiazolin-3-one (BBIT), methylisothiazolinone, N-octyl-4-isothiazoline-3-one, 4,5-dichloro-N-octyl-4-isothiazoline-3-one (DCOIT), 1,2-benzisothiazolin-3-one, n-butyl-1,2-isothiazoline-3-one, and didecyldimethylammonium chloride (DDAC).

[0023] In one embodiment, the mildew preventer is a composite mildew preventer of 2-octyl-4-isothiazoline-3-one (OIT) and 4,5-dichloro-N-octyl-4-isothiazoline-3-one (DCOIT) in a weight ratio of 1:2.

[0024] In one embodiment, the double-layer microcapsule mildew inhibitor is prepared by the following steps:

[0025] 1) mixing the mildewcide with water to form a mildewcide solution;

[0026] 2) mixing sodium alginate, the antifungal agent solution and water to form a mixed solution; mixing calcium chloride and water to form a calcium chloride solution; then adding the mixed solution to the calcium chloride solution, allowing to stand and filtering to form a single-layer microcapsule antifungal agent;

[0027] 3) At room temperature, acetic acid and chitosan are added to water in sequence and mixed to form a microcapsule wall material solution;

[0028] 4) adding the single-layer microcapsule mildew preventer into the microcapsule wall material solution, stirring, washing, filtering and drying to obtain the double-layer microcapsule mildew preventer.

[0029] In one embodiment, mixing the mildewcide with water to form a mildewcide solution may include adding 1-3 parts by weight of mildewcide to 10-30 parts by weight of water, and stirring at a speed of 300-600 r / min to form a mildewcide solution;

[0030] In one embodiment, mixing sodium alginate, the anti-mildew solution and water to form a mixed solution may include sequentially adding 1-3 parts by weight of sodium alginate and the prepared anti-mildew solution to 20-40 parts by weight of water, and stirring at a speed of 300-600 r / min to form a mixed solution.

[0031] In one embodiment, mixing calcium chloride with water to form a calcium chloride solution may include mixing 0.5-2 parts by weight of calcium chloride with 30-50 parts by weight of water to form the calcium chloride solution.

[0032] In one embodiment, adding the mixed solution to the calcium chloride solution, letting it stand and filtering to form a single-layer microcapsule mildew preventer may include adding the obtained mixed solution to the calcium chloride solution, letting it stand for 5-30 minutes, and filtering to form a single-layer microcapsule mildew preventer.

[0033] In one embodiment, at room temperature, acetic acid and chitosan are sequentially added to water, and the mixture is mixed to form a microcapsule wall material solution, which may include sequentially adding 5-10 parts by weight of acetic acid and 5-10 parts by weight of chitosan to 80-100 parts by weight of water at room temperature, and stirring evenly at a speed of 300-700 r / min to form a microcapsule wall material solution.

[0034] In one embodiment, obtaining the double-layer microcapsule mildew preventer may include adding a single-layer microcapsule mildew preventer into a microcapsule wall material solution, stirring at a speed of 500-1000 r / min for 20-60 min, washing and filtering with distilled water for multiple times, and then drying to obtain the double-layer microcapsule mildew preventer.

[0035] On the other hand, the present application provides a method for preparing the above-mentioned silica aerogel slurry, the method comprising the following steps:

[0036] 1) Weigh each component;

[0037] 2) adding anionic surfactant, polymer electrolyte, suspending agent, defoaming agent and double-layer microcapsule mildew inhibitor into water, and stirring at normal temperature and pressure to form a composite dispersed solution;

[0038] 3) stirring and mixing the hydrophobic silica aerogel powder and the composite dispersed solution, and then adding a pH adjuster to adjust the pH value of the solution to 7.5-9.5 to obtain an initial slurry;

[0039] 4) The initial slurry is subjected to a vacuum degassing process to prepare the silica aerogel slurry.

[0040] In one embodiment, in step 2), the stirring speed may be 300-500 r / min, and the stirring time may be 5-15 minutes.

[0041] In one embodiment, in step 3), the stirring speed may be 1000-4500 r / min, and the stirring time may be 5-30 minutes.

[0042] The present application introduces a ternary composite system into an aqueous system, utilizing the synergistic steric hindrance of small molecules and macromolecules, and the hydrogen bond association between the suspension stabilizer and the water molecules to form a high steric repulsion; the polymer ions and small molecule ions formed by the dissolution of polymer electrolytes and surfactants in water are adsorbed on the surface of aerogel particles to form a double-thickness stable dispersion layer of charged ions; at the same time, by adjusting the pH range of the slurry (such as a pH range of 7.5-9.5), the absolute value of the Zeta potential of the slurry is further increased, and the Zeta potential with an absolute value of the surface potential of the aerogel particles greater than 20mV is achieved, forming a strong electrostatic repulsion between the particles, thereby ensuring the dispersion stability of the slurry.

[0043] The present application introduces a double-layer microcapsule mildew preventer into the aerogel slurry, wherein the mildew preventer is used as the core material, and the wall material forms a double-layer microcapsule outside the core material, thereby achieving a double-wrapping protection effect on the mildew preventer and achieving efficient and safe mildew prevention performance. The double-layer microcapsule mildew preventer of the present application controls the release speed of mildew-proof substances through microcapsules, continuously releases mildew-proof substances, achieves a long-term mildew prevention effect, can effectively improve the mildew problem of aerogel slurry after long-term storage, and improves the long-term stability of the mildew-proof effect of aerogel slurry.

[0044] The present application improves the stability of the mildew inhibitor by adopting a double-layer microcapsule mildew inhibitor, thereby avoiding the decomposition, oxidation and loss of the mildew inhibitor's active ingredients caused by environmental factors such as light, temperature and other chemical substances.

[0045] The present application enhances the compounding ability of the mildew preventer with other aerogel slurry components (i.e., the surfactant, polymer electrolyte, and suspending agent ternary composite dispersion system of the present application) by adopting a double-layer microcapsule mildew preventer, thereby not only achieving the desired mildew prevention effect with a smaller addition amount, but also avoiding adverse effects on the performance of the aerogel slurry obtained by the ternary composite dispersion system of the present application, so that the prepared aerogel slurry still maintains high hydrophobicity and low thermal conductivity after drying, and the prepared aerogel slurry maintains long-lasting stability.

[0046] The present application improves the safety of the product and reduces the harm to human health and environmental pollution by using a double-layer microcapsule mildew inhibitor in combination with other slurry components.

[0047] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present application more clear, the embodiments of the present application are described in detail below. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0049] Unless otherwise specified, the materials used in the following examples and comparative examples are commercially available.

[0050] The hydrophobic silica aerogel powder in the following examples and comparative examples may have an average particle size of about 50 μm and a bulk density of about 80 kg / m 3 , a commercially available product with a thermal conductivity of about 0.019 W / m·k and a contact angle of about 148°.

[0051] Example 1

[0052] (1) 2 parts by weight of a mildew preventer (DCOIT) was added to 25 parts by weight of water and stirred at a speed of 600 r / min to form a mildew preventer solution.

[0053] (2) 3 parts by weight of sodium alginate and 3 parts by weight of antifungal solution were added to 40 parts by weight of water in sequence, and stirred at a speed of 600 r / min to form a mixed solution; 2 parts by weight of calcium chloride were mixed with 50 parts by weight of water to form a calcium chloride solution; then the mixed solution was added to the calcium chloride solution, allowed to stand for 25 minutes, and filtered to form a single-layer microcapsule antifungal agent.

[0054] (3) At room temperature, 5 parts by weight of acetic acid and 10 parts by weight of chitosan were added to 80 parts by weight of water in sequence, and stirred at a speed of 500 r / min to form a second layer of microcapsule wall material solution.

[0055] (4) adding the single-layer microcapsule mildew preventer into the microcapsule wall material solution, stirring at a speed of 500 r / min for 50 min, washing and filtering with distilled water for multiple times, and then drying to obtain the double-layer microcapsule mildew preventer.

[0056] (5) 0.1 parts by weight of sodium dodecylbenzene sulfonate SDBS, 0.2 parts by weight of polyacrylamide (PAM) with a number average molecular weight of 2,000,000, 0.01 parts by weight of hydroxyethyl cellulose HEC, 0.004 parts by weight of a combination of Deco 901W and BASF 2410 defoamers (weight ratio of 1:3), and 0.02 parts by weight of a double-layer microcapsule mildew inhibitor were added to 60 parts by weight of deionized water, and stirred at a speed of 500 r / min for 10 minutes in a high-speed disperser at room temperature and pressure to obtain a uniformly mixed and stable composite dispersion solution.

[0057] (6) adding 6 parts by weight of hydrophobic silica aerogel powder to the composite dispersed solution, stirring at a speed of 1000 r / min until the hydrophobic silica aerogel powder is completely immersed in the composite dispersed solution, and then stirring at a speed of 2500 r / min for 30 minutes, adding 0.005-0.01 parts by weight of ammonia water to adjust the pH value of the slurry to about 9.5, and obtaining an initial slurry; and performing a vacuum degassing process on the initial slurry to prepare a silica aerogel slurry.

[0058] Example 2-3

[0059] The preparation method of Example 2-3 is similar to that of Example 1, except that a composite mildew preventer of 2-n-octyl-4-isothiazoline-3-one (OIT) and 4,5-dichloro-N-octyl-4-isothiazoline-3-one (DCOIT) with a weight ratio of 1:2 is used in the preparation of the double-layer microcapsule mildew preventer in Example 2 and Example 3, and the pH value of the prepared aerogel slurry is different, and the pH value is shown in Table 1 below.

[0060] Comparative Example 1

[0061] (1) 0.1 parts by weight of sodium dodecylbenzene sulfonate SDBS, 0.2 parts by weight of polyacrylamide (PAM) having a number average molecular weight of 2,000,000, 0.01 parts by weight of hydroxyethyl cellulose HEC, 0.004 parts by weight of a combination of Deco 901W and BASF 2410 defoamer (weight ratio of 1:3), and 0.02 parts by weight of DCOIT were added to 60 parts by weight of deionized water, and stirred at a speed of 500 r / min for 10 minutes in a high-speed disperser at room temperature and pressure to obtain a uniformly mixed and stable composite dispersion solution.

[0062] (2) adding 6 parts by weight of hydrophobic silica aerogel powder to the composite dispersed solution, stirring at a speed of 1000 r / min until the hydrophobic silica aerogel powder is completely immersed in the composite dispersed solution, and then stirring at a speed of 2500 r / min for 30 minutes, adding 0.005-0.01 parts by weight of ammonia water to adjust the pH value of the slurry to about 9.5, and obtaining an initial slurry; and performing a vacuum degassing process on the initial slurry to prepare a silica aerogel slurry.

[0063] Comparative Example 2

[0064] (1) 0.1 parts by weight of sodium dodecylbenzene sulfonate SDBS, 0.2 parts by weight of polyacrylamide (PAM) having a number average molecular weight of 2,000,000, 0.01 parts by weight of hydroxyethyl cellulose HEC, 0.004 parts by weight of a combination of Deco 901W and BASF 2410 defoamer (weight ratio of 1:3), and 0.02 parts by weight of a composite antifungal agent (OIT:DCOIT=1:2) were added to 60 parts by weight of deionized water, and stirred at a speed of 500 r / min for 10 minutes in a high-speed disperser at room temperature and pressure to obtain a uniformly mixed and stable composite dispersion solution.

[0065] (2) adding 6 parts by weight of hydrophobic silica aerogel powder to the composite dispersed solution, stirring at a speed of 1000 r / min until the hydrophobic silica aerogel powder is completely immersed in the composite dispersed solution, and then stirring at a speed of 2500 r / min for 30 minutes, adding 0.005-0.01 parts by weight of ammonia water to adjust the pH value of the slurry to about 9.5, and obtaining an initial slurry; and performing a vacuum degassing process on the initial slurry to prepare a silica aerogel slurry.

[0066] Comparative Example 3

[0067] (1) 0.1 parts by weight of sodium dodecylbenzene sulfonate SDBS, 0.2 parts by weight of polyacrylamide (PAM) having a number average molecular weight of 2,000,000, 0.01 parts by weight of hydroxyethyl cellulose HEC, 0.004 parts by weight of Deco 901W and BASF 2410 defoamer (weight ratio of 1:3) were added to 60 parts by weight of deionized water, and stirred at a speed of 500 r / min for 10 minutes in a high-speed disperser at room temperature and pressure to obtain a uniformly mixed and stable composite dispersion solution.

[0068] (2) adding 6 parts by weight of hydrophobic silica aerogel powder to the composite dispersed solution, stirring at a speed of 1000 r / min until the hydrophobic silica aerogel powder is completely immersed in the composite dispersed solution, and then stirring at a speed of 2500 r / min for 30 minutes, adding 0.005-0.01 parts by weight of ammonia water to adjust the pH value of the slurry to about 9.5, and obtaining an initial slurry; and performing a vacuum degassing process on the initial slurry to prepare a silica aerogel slurry.

[0069] Comparative Examples 4-7

[0070] The preparation methods of Comparative Examples 4-7 are substantially the same as those of Example 1, but only include aerogel slurries prepared by a single dispersion system or a binary composite dispersion system. The dispersion systems and proportions of Comparative Examples 4-7 are shown in Table 1 below.

[0071] Table 1

[0072] project Dispersed system Slurry pH Number of copies Example 2 SDBS / PAM / HEC 8.9 0.1 / 0.2 / 0.01 Example 3 SDBS / PAM / HEC 9.1 0.1 / 0.2 / 0.01 Comparative Example 4 SDBS 9.2 0.1 Comparative Example 5 PAM 9.5 0.2 Comparative Example 6 SDBS / PAM 9.3 0.1 / 0.2 Comparative Example 7 SDBS / HEC 9.2 0.1 / 0.01

[0073] Performance Testing

[0074] The silica aerogel slurry prepared in Examples 1-3 and Comparative Examples 1-7 was subjected to a Zeta potential test, and the samples were dried at 60°C for thermal conductivity and contact angle tests. The thermal conductivity was tested according to the national standard GB / T 10297-2015. Further, regarding the long-term static stability of the aerogel slurry, the aerogel slurry prepared in Examples 1-3 and Comparative Examples 1-7 was tested. The slurry was placed in a constant temperature and humidity environment with a temperature of 25±2°C and a relative humidity of 40-50%. After standing for 180 days, it was tested whether it was moldy after long-term placement, and whether it had unstable phenomena such as sedimentation, stratification, and waterlogging. The test results are shown in Table 2 below.

[0075] Table 2

[0076]

[0077] According to the results in Table 2, the aerogel slurry prepared in Comparative Example 3 did not add mildew inhibitors. After standing in a constant temperature and humidity environment for 180 days, the absolute value of the Zeta potential was greater than 20 mV, and no obvious sedimentation, stratification or water seepage occurred. However, due to the lack of mildew inhibitors, severe mildew occurred, and large black spots appeared in the mildewed part, which seriously affected the apparent color of the aerogel slurry. At the same time, there were problems of high thermal conductivity and low contact angle, which adversely affected the thermal conductivity and hydrophobicity of the aerogel slurry. This shows that mildew will seriously affect the product quality of the aerogel slurry.

[0078] A single mildewproofing agent and a composite mildewproofing agent were added to the aerogel slurries prepared in Comparative Examples 1 and 2, respectively. After standing in a constant temperature and humidity environment for 180 days, no serious mildew occurred. After drying, the aerogel slurry still maintained a low thermal conductivity and a high contact angle, which shows that the thermal conductivity and hydrophobicity of the aerogel slurry were not affected. However, there were a small amount of mold black spots on the surface of the slurries in the two comparative examples, and there were signs of mildew. This may be due to the decomposition and loss of the mildewproofing agent during the preparation and storage of the slurry, resulting in a weakening of its mildewproofing effect. After standing, the slurries in the two comparative examples also showed a phenomenon of stratification. This may be because, although the absolute value of the Zeta potential of the aerogel slurry is greater than 20mV, the addition of the mildewproofing agent affects the compounding between other components in the aerogel slurry, resulting in the instability of the slurry during long-term placement.

[0079] In the aerogel slurry prepared in Comparative Examples 4-7, a single dispersant or a binary composite dispersant was added respectively, and the mildewproof agent was in the form of a double-layer microcapsule composite mildewproof agent. After standing for 180 days in a constant temperature and humidity environment, the aerogel slurry did not suffer from serious mildew and still maintained a low thermal conductivity and a high contact angle after drying, which shows that the double-layer microcapsule composite mildewproof agent has an excellent mildewproof effect and has no adverse effect on the thermal conductivity and hydrophobicity of the aerogel slurry. However, the absolute value of the Zeta potential of the aerogel slurry prepared by a single dispersion system or a binary composite dispersion system is less than 20mV, the electrostatic and steric repulsion is small, and the problem of stratification occurs after standing, which may be due to the difficulty of ensuring the stability of the system in a single dispersion system or a binary composite dispersion system.

[0080] On the contrary, the aerogel slurry prepared in Examples 1-3 of the present application adopts a ternary composite dispersion system. After standing for 180 days in a constant temperature and humidity environment, the aerogel slurry still retains its anti-mildew effect, no mildew problem occurs, and after drying, the thermal conductivity is still low and the contact angle is high, and the composite with other components of the aerogel slurry is not affected. The slurry quality remains stable, and there is no obvious instability such as sedimentation, stratification or water seepage. This may be due to the synergy of small molecules and macromolecules and the hydrogen bonding of the suspension stabilizer with water molecules to increase the steric repulsion and ensure the stability of the aerogel slurry; at the same time, a double-layer microcapsule composite mildew inhibitor is added, and chitosan and sodium alginate are used to double-wrap the composite mildew inhibitor for protection, which inhibits the decomposition and loss of the mildew inhibitor during the slurry preparation and storage process.

[0081] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A silica aerogel slurry, characterized in that: The silica aerogel slurry is prepared from the following materials, which are, by weight, 10-90 parts of water, 1-25 parts of hydrophobic silica aerogel powder, 0.01-3 parts of anionic surfactant, 0.01-0.9 parts of polymer electrolyte, 0.01-1 parts of suspending agent, 0.001-0.01 parts of pH regulator, 0.001-0.02 parts of defoaming agent and 0.001-0.01 parts of double-layer microcapsule mildewproof agent, wherein the double-layer microcapsule mildewproof agent comprises, by weight, 1-3 parts of mildewproof agent, 1-3 parts of sodium alginate, 0.5-2 parts of calcium chloride, 5-10 parts of acetic acid, 5-10 parts of chitosan and 100-200 parts of water.

2. The silica aerogel slurry according to claim 1, characterized in that: The anionic surfactant is selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl polyoxyethylene ether sulfate, sodium alkyl polyoxyethylene ether carboxylate, sodium dodecyl sulfonate, sodium methylene bisnaphthalene sulfonate and sodium oleoyl methyl taurate; optionally, the anionic surfactant is sodium dodecylbenzene sulfonate.

3. The silica aerogel slurry according to claim 1, characterized in that: The suspending agent is selected from one or more of hydroxypropyl methylcellulose, methylcellulose, hydroxyethyl cellulose and carboxymethyl cellulose; optionally, the suspending agent is hydroxyethyl cellulose.

4. The silica aerogel slurry according to claim 1, characterized in that: The polymer electrolyte is selected from one or more of sodium polyacrylate, ammonium polyacrylate, polyacrylamide, sodium polystyrene sulfonate and polystyrene-maleic anhydride copolymer; optionally, the polymer electrolyte is polyacrylamide.

5. The silica aerogel slurry according to claim 4, characterized in that: The polymer electrolyte has a number average molecular weight in the range of 500,000-3,000,000; optionally, the polymer electrolyte has a number average molecular weight in the range of 2,000,000-3,000,000.

6. The silica aerogel slurry according to claim 1, characterized in that: The defoamer is selected from one or more of BASF 2410 defoamer, Nopco 1375, Nopco 1370, Beike 024 and Digo 901W; optionally, the defoamer is a combination of Digo 901W and BASF 2410 defoamer in a weight ratio of 1:1-5; and / or, The hydrophobic silica aerogel powder has a particle size of 0.5 μm-500 μm and a bulk density of 60 kg / m 3 -120 kg / m 3 , thermal conductivity is 0.018W / m·k-0.021W / m·k and contact angle is 146°-149°.

7. The silica aerogel slurry according to claim 1, characterized in that: The water is distilled water or deionized water; and / or The pH regulator is selected from one or more of ammonia water, triethylamine, dimethylethanolamine, and 2-aminomethyl-1-propanol; and / or The pH of the silica aerogel slurry is in the range of 7.5-9.

5.

8. The silica aerogel slurry according to any one of claims 1 to 7, characterized in that: The double-layer microcapsule mildew inhibitor is prepared by the following steps: 1) mixing the mildewcide with water to form a mildewcide solution; 2) mixing sodium alginate, the antifungal agent solution and water to form a mixed solution; mixing calcium chloride and water to form a calcium chloride solution; then adding the mixed solution to the calcium chloride solution, allowing to stand and filtering to form a single-layer microcapsule antifungal agent; 3) At room temperature, acetic acid and chitosan are added to water in sequence and mixed to form a microcapsule wall material solution; 4) adding the single-layer microcapsule mildew preventer into the microcapsule wall material solution, stirring, washing, filtering and drying to obtain the double-layer microcapsule mildew preventer.

9. The silica aerogel slurry according to any one of claims 1 to 7, characterized in that: The mildew preventer is selected from one or more of 2-n-octyl-4-isothiazoline-3-one, 2-butyl-1,2-benzisothiazolin-3-one, methylisothiazolinone, N-octyl-4-isothiazoline-3-one, 4,5-dichloro-N-octyl-4-isothiazoline-3-one, 1,2-benzisothiazolin-3-one, n-butyl-1,2-isothiazoline-3-one, and didecyldimethylammonium chloride; optionally, the mildew preventer is a composite mildew preventer of 2-n-octyl-4-isothiazoline-3-one and 4,5-dichloro-N-octyl-4-isothiazoline-3-one in a weight ratio of 1:

2.

10. A method for preparing a silica aerogel slurry according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: 1) Weigh each component; 2) adding anionic surfactant, polymer electrolyte, suspending agent, defoaming agent and double-layer microcapsule mildew inhibitor into water, and stirring at normal temperature and pressure to form a composite dispersed solution; 3) stirring and mixing the hydrophobic silica aerogel powder and the composite dispersed solution, and then adding a pH adjuster to adjust the pH value of the solution to 7.5-9.5 to obtain an initial slurry; 4) performing a vacuum degassing process on the initial slurry to obtain the silica aerogel slurry.

Images