A kind of aerogel thermal insulation coating and preparation method thereof

Abstract

This application relates to the field of architectural coatings, and discloses an aerogel thermal insulation coating and its preparation method. The aerogel thermal insulation coating is prepared from the following raw materials in parts by weight: 25-45 parts polyethylene glycol, 18-38 parts diisocyanate, 15-30 parts silica aerogel, 0.1-0.3 parts catalyst, 8-16 parts chain extender, 1.5-3.5 parts adhesion promoter, 3-6 parts neutralizer, and 80-110 parts water. The preparation method involves: reacting polyethylene glycol, diisocyanate, and catalyst; adding chain extender; adding adhesion promoter; adding neutralizer and water for emulsification; and adding silica aerogel for further reaction. This application uses a previously used stepwise reaction method, which is simple to prepare. The resulting aerogel thermal insulation coating has good thermal insulation performance, light transmittance, and adhesion performance, and can stably bond with architectural glass, showing little tendency to detach over long-term use.

Description

Technical Field

[0001] The present application relates to the field of architectural coatings, and more specifically, to an aerogel thermal insulation coating and a preparation method thereof. Background Art

[0002] With the large number of civil buildings put into use in my country every year, the use of air conditioners, heating equipment, etc. has continued to increase. Building energy conservation has become an important aspect of reducing social energy consumption. At present, building energy consumption accounts for about 30% of the total social energy consumption. Among them, glass, as a building material, has the advantages of corrosion resistance, erosion resistance and easy cleaning. However, at the same time, glass also has the disadvantages of high heat transfer and low heat storage. The use of glass in building materials is likely to generate large energy consumption. Therefore, some studies have proposed to improve the coating of functional coatings on the glass surface.

[0003] At present, the functional coatings applied to glass surfaces are water-based polyurethane coatings or water-based acrylic coatings. The thermal insulation performance of these functional coatings is improved by adding thermal insulation fillers. Commonly used thermal insulation fillers include hollow glass beads, titanium dioxide, etc. These thermal insulation fillers are added to the functional coatings. The obtained functional coatings are easily separated from the architectural glass under conditions of long-term wind and sun exposure, which reduces the thermal insulation and other performance of the functional coatings. Therefore, further improvement is needed. Summary of the invention

[0004] In order to solve the problem that conventional functional coatings are easily separated from the glass surface when applied to architectural glass, thereby reducing the performance of the functional coatings, the present application provides an aerogel thermal insulation coating and a preparation method thereof.

[0005] In the first aspect, the present application provides an aerogel thermal insulation coating, which adopts the following technical solution:

[0006] An aerogel thermal insulation coating is prepared from the following raw materials in parts by weight:

[0007] 25-45 parts of polyethylene glycol

[0008] 18-38 parts of diisocyanate

[0009] 15-30 parts of silica aerogel

[0010] Catalyst 0.1-0.3 parts

[0011] Chain extender 8-16 parts

[0012] Adhesion promoter 1.5-3.5 parts 3-6 parts of neutralizer

[0013] 80-110 parts of water.

[0014] By adopting the above technical scheme, under the action of the catalyst, the polyethylene glycol provides alcohol hydroxyl group and the isocyanate group of the diisocyanate to react, the chain extender has a good chain extension effect, thereby forming an aqueous polyurethane emulsion with a better soft segment and hard segment ratio, the adhesion promoter has a good adhesion promotion effect, and can further improve the adhesion of the prepared aerogel thermal insulation coating, the neutralizer can well improve the light transmittance and system stability of the prepared aerogel thermal insulation coating, and by introducing silica aerogel into the prepared aqueous polyurethane emulsion system, the silica aerogel has nano-micropores and a three-dimensional network structure, so it has excellent properties such as ultra-low thermal conductivity, low density and high porosity, and the silica aerogel has good interfacial bonding compatibility with the aqueous polyurethane emulsion system, so it can be evenly dispersed, and the aerogel thermal insulation coating prepared in this way has good thermal insulation performance and adhesion, is coated on the glass surface to form a dense transparent film, has good light transmittance, good bonding stability, and can be widely used in architectural glass to reduce the energy consumption of glass buildings.

[0015] Preferably, the silica aerogel is prepared by the following steps:

[0016] A1. Add 15-25 parts of ethyl orthosilicate to 30-50 parts of ethanol by weight, mix well, add 3-6 parts of water, control the temperature to 20-35°C, add 0.3-0.8 parts of hydrofluoric acid for hydrolysis, react for 10-20 minutes, and obtain a prepolymer;

[0017] A2, adding 1-2 parts of ammonia water and 1.5-2.5 parts of polyethylene glycol 800 and diethylene glycol in a weight ratio of 1: (0.2-0.4) to the prepolymer, reacting for 20-40 minutes to obtain a silica aerogel matrix;

[0018] A3. Add 10-20 parts of water to the prepared silica aerogel matrix, place it at a temperature of 55-65° C., let it stand for 6-12 hours, and then filter it;

[0019] A4. Add 1-3 parts of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane in a dosage ratio of 1:(0.5-0.7) to the silica aerogel matrix prepared in step A3, stir evenly, add 50-70 parts of ethanol for solvent replacement, and then dry to obtain silica aerogel.

[0020] By adopting the above technical scheme, first, tetraethyl orthosilicate is hydrolyzed in an acidic alcohol aqueous solution to obtain a prepolymer, and the prepolymer is further subjected to a condensation reaction under the action of ammonia water to obtain a silica aerogel matrix. Both polyethylene glycol 800 and diethylene glycol have relatively good chain segment length and chain segment flexibility. The addition of polyethylene glycol 800 and diethylene glycol can make the network gap distribution of the obtained aerogel matrix uniform, and can improve the strength of the skeleton of the obtained silica aerogel matrix, reduce the situation of skeleton shrinkage or cracking caused by uneven network gaps, and further improve the structural stability of the obtained silica aerogel. Water is added to the silica aerogel matrix, and aging is carried out under relatively good temperature conditions to further improve the structural stability of the silica aerogel, and sufficient condensation reaction is carried out to prepare. To obtain a silica aerogel with higher transparency, a preferably proportion of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane are added to the system as an interfacial crosslinking agent, and the silica aerogel thus obtained is further cross-condensed in the three-dimensional network molecular structure of the interfacial crosslinking agent, which can further improve the skeleton stability, dispersibility and adhesion of the silica aerogel obtained, and then solvent replacement and drying are performed to form a silica aerogel with a relatively uniform and large porosity. The silica aerogel thus obtained has a stable and uniform pore structure with a large specific surface area, and the silica aerogel can be evenly dispersed in the aqueous polyurethane emulsion system, which can improve the thermal insulation, transparency and adhesion stability of the aerogel thermal insulation coating, thereby preparing an aerogel thermal insulation coating with good thermal insulation performance and adhesion.

[0021] Preferably, the polyethylene glycol is one or a combination of polyethylene glycol 1000, polyethylene glycol 1500, polyethylene glycol 2000, and polyethylene glycol 3000.

[0022] By adopting the above technical scheme and using the above-mentioned polyethylene glycol with a relatively optimal molecular weight to provide alcoholic hydroxyl groups, the prepared aerogel thermal insulation coating has good flexibility and adhesion.

[0023] Preferably, the diisocyanate is isophorone diisocyanate and / or hexamethylene diisocyanate.

[0024] By adopting the above technical scheme, isophorone diisocyanate and hexamethylene diisocyanate are fatty diisocyanates, and the aerogel thermal insulation coating prepared by using the diisocyanates has good system stability and bonding stability.

[0025] Preferably, the chain extender is composed of dimethylolpropionic acid and butanediol in a weight ratio of 1:(0.4-0.6).

[0026] By adopting the above technical scheme, dihydroxymethylpropionic acid is used as a carboxylic acid type chain extender, butanediol is used as a small molecule alcohol chain extender, and a small molecule polyol and carboxylic acid are used as chain extenders in a relatively optimal ratio to prepare an aerogel thermal insulation coating with good water resistance and adhesion properties.

[0027] Preferably, the adhesion promoter is composed of hydroxy fluorosilicone oil and polyethylene glycol glycidyl ether in a dosage ratio of 1:(0.1-0.3).

[0028] By adopting the above technical scheme, hydroxyl fluorosilicone oil is a hydroxyl-terminated oligomer. Due to the introduction of trifluoropropyl group on the silicon atom, it has lower surface tension and better adhesion. Polyethylene glycol glycidyl ether has a molecular structure with ether group as the main chain and epoxy group at the end. A better proportion of hydroxyl fluorosilicone oil and polyethylene glycol glycidyl ether can be further cross-linked with diisocyanate to form a molecular chain interpenetrating network structure. The aerogel thermal insulation coating prepared in this way further has a stable dispersion system and adhesion.

[0029] Preferably, the catalyst is any one of dibutyltin dioctanoate and stannous octoate.

[0030] By adopting the above technical solution, the above catalyst has good catalytic activity and catalytic stability, thereby improving the reaction efficiency of the reaction.

[0031] Preferably, the neutralizer is composed of a first neutralizer and a second neutralizer in a dosage ratio of 1:(0.3-0.5), the first neutralizer is triethylamine and / or ammonia water, and the second neutralizer is diethylamine.

[0032] By adopting the above technical scheme, the first neutralizer and the second neutralizer are compounded in a preferred ratio and the neutralization degree of the aqueous polyurethane emulsion system is adjusted, so that the aqueous polyurethane emulsion prepared has good adhesion and transparency, and the light transmittance and adhesion of the prepared aerogel thermal insulation coating are improved.

[0033] In a second aspect, the present application provides a method for preparing an aerogel thermal insulation coating, which adopts the following technical solution:

[0034] A method for preparing an aerogel thermal insulation coating comprises the following preparation steps:

[0035] S1, adding polyethylene glycol, diisocyanate and catalyst into a reaction device, heating to 95-120°C for reaction, and obtaining reactant A;

[0036] S2, adding a chain extender to reactant A, cooling to 70-80°C for reaction, and obtaining reactant B;

[0037] S3, adding an adhesion promoter to reactant B, stirring evenly, cooling to 45-60° C., adding a first neutralizer, stirring and emulsifying, and then adding water, stirring and emulsifying to obtain reactant C;

[0038] S4, continue to add the second neutralizing agent to the reactant C and mix and stir to obtain an aqueous polyurethane emulsion;

[0039] S5. Add silica aerogel to the aqueous polyurethane emulsion, and prepare the aerogel thermal insulation coating after stirring and dispersing.

[0040] By adopting the above technical scheme, first, under the action of a catalyst and a relatively optimal temperature, polyethylene glycol and diisocyanate react to obtain a reactant A terminated with an isocyanate group, and the reactant A further undergoes a chain extension reaction with a chain extender under relatively optimal temperature conditions to obtain a reactant B combining a soft segment and a hard segment, and then an adhesion promoter is added to further crosslink the molecular chain segments to obtain a polyurethane molecular chain segment with an interpenetrating network structure of a molecular chain, and then a first neutralizing agent is added to stir and emulsify, and under the neutralization action of the relatively optimal first neutralizing agent, the system stability of the obtained reactant C is improved, and then water is added for further emulsification, and then the addition is continued after emulsification. A second neutralizing agent is added for neutralization and emulsification, so as to further improve the emulsion stability of the prepared aqueous polyurethane emulsion, so that the prepared aqueous polyurethane emulsion has good transparency and system dispersion stability at the same time, and has good molecular emulsification stability while also having good emulsion intermolecular force, which can improve the adhesion performance of the prepared aerogel thermal insulation coating, and then the silica aerogel is added to the aqueous polyurethane emulsion, and the silica aerogel can be stably mixed and dispersed with the aqueous polyurethane emulsion with relatively stable molecular chain bond force, so that the aerogel thermal insulation coating prepared in this way has good thermal insulation, adhesion, stability and light transmittance.

[0041] Preferably, in the step S1, the cyanide-hydroxyl ratio of the obtained reactant A is (3.9-4.1):1, in the step S2, the cyanide-hydroxyl ratio of the obtained reactant B is (1.1-1.4):1, and in the step S5, after adding the silica aerogel, high-speed stirring is first performed at a speed of 1000-1500 r / min, and then low-speed stirring is performed at a speed of 400-600 r / min.

[0042] By adopting the above technical scheme, the cyanide-hydroxyl ratio of reactant A is controlled to form a soft segment polyurethane structure with a relatively optimal length chain segment, so that the water-based polyurethane prepared has good molecular flexibility and adhesion, and the cyanide-hydroxyl ratio of reactant B is controlled, and reactant A is chain extended on the basis of reactant A, so that the hard segment and soft segment of the prepared polyurethane system have a relatively optimal ratio, and an aerogel thermal insulation coating with good hardness, molecular flexibility and adhesion is prepared under the condition of sufficient reaction. After adding silica aerogel, at a relatively optimal stirring rate, the silica aerogel is uniformly dispersed in the water-based polyurethane emulsion to form a stable interface bonding dispersion system, so that the aerogel thermal insulation coating prepared has good system stability.

[0043] In summary, this application has the following beneficial effects:

[0044] 1. An aerogel thermal insulation coating of the present application is prepared by reacting polyethylene glycol and diisocyanate under the action of a catalyst, and preparing an aqueous polyurethane emulsion under the further reaction of a chain extender and an adhesion promoter and the emulsification of a neutralizer and water. The aqueous polyurethane emulsion is used as a matrix, and silica aerogel with excellent properties such as low thermal conductivity, low density and high porosity is introduced. The aerogel thermal insulation coating prepared by uniformly and stably combining the silica aerogel and the aqueous polyurethane emulsion has good thermal insulation, adhesion and stability for architectural glass, and has good light transmittance and will not affect the appearance of the architectural glass.

[0045] 2. The silica aerogel prepared in the present application is hydrolyzed under acidic conditions using n-butyl silicate, and then subjected to a condensation reaction under alkaline conditions and the combined action of polyethylene glycol 800 and diethylene glycol, and then subjected to an aging treatment. Finally, a cross-linking modification is performed using a preferably proportion of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane, and then the aerogel is prepared by solvent replacement and drying. The aerogel has a relatively uniform void structure, good skeleton strength, large porosity, good thermal insulation performance, dispersibility and adhesion. The aerogel thermal insulation coating prepared in this way has good thermal insulation, adhesion and light transmittance.

[0046] 3. Using a better ratio of hydroxy fluorosilicone oil and polyethylene glycol glycidyl ether as adhesion promoters can improve the adhesion and thermal insulation of the aerogel thermal insulation coating.

[0047] 4. The preparation method of the present application obtains an aerogel thermal insulation coating with a dispersed and stable system by carrying out reactions in steps. DETAILED DESCRIPTION

[0048] The present application is further described in detail below with reference to the embodiments.

[0049] The following are the sources and specifications of some raw materials of this application. The raw materials in the preparation examples and embodiments of this application can be obtained from the market. The raw materials used in this application include but are not limited to the models and manufacturers listed below. Raw materials of other manufacturers with the same specifications and performance can be used:

[0050] 1. Hydroxyfluorosilicone oil: purity 99%, hydroxyl content 1-3%, viscosity 50-150mm 2 / s;

[0051] 2. Ammonia: industrial grade, content 25-28%;

[0052] 3. Commercially available silica aerogel: Brand: Cabot, Model: MT1100 silica aerogel, particle size 2-10μm.

[0053] Preparation example of silica aerogel

[0054] Preparation Example 1

[0055] Preparation Example 1 discloses a silica aerogel, which is prepared by the following steps:

[0056] A1. By weight, 1.5 kg of tetraethyl orthosilicate was added to 3 kg of ethanol, mixed evenly, and then 0.3 kg of water was added. The temperature was controlled at 20°C, and 0.03 kg of hydrofluoric acid was added for hydrolysis. After reacting for 10 minutes, a prepolymer was obtained.

[0057] A2, adding 0.1 kg of ammonia water and 0.15 kg of polyethylene glycol 800 and diethylene glycol in a weight ratio of 1:0.2 to the prepolymer, reacting for 20 minutes to obtain a silica aerogel matrix;

[0058] A3. Add 1 kg of water to the prepared silica aerogel matrix, place it at a temperature of 55°C, let it stand for 6 hours, and then filter it;

[0059] A4. Add 0.1 kg of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane in a weight ratio of 1:0.5 to the silica aerogel matrix obtained in step A3, mix for 10 minutes, add 5 kg of ethanol for solvent replacement after mixing evenly, and then evaporate and dry at normal pressure at a temperature of 90° C. to obtain silica aerogel after drying.

[0060] Preparation Example 2-3

[0061] The difference between Preparation Example 2-3 and Preparation Example 1 is that the amount of raw materials used and the preparation conditions are different, see Table 1 below for details.

[0062] Table 1 Raw material dosage and preparation conditions of Preparation Examples 1-3

[0063]

[0064] Preparation Comparative Example 1

[0065] The difference between Preparation Example 1 and Preparation Example 1 is that the usage ratio of polyethylene glycol 800 and diethylene glycol is different. The usage ratio of polyethylene glycol 800 and diethylene glycol in Preparation Example 1 is 1:0.1, and the others are the same as Preparation Example 1.

[0066] Preparation Comparative Example 2

[0067] The difference between Preparation Example 2 and Preparation Example 1 is that in Preparation Example 2, an equal amount of diethylene glycol is replaced by polyethylene glycol 800, and the rest is the same as Preparation Example 1.

[0068] Preparation Comparative Example 3

[0069] The difference between Preparation Example 3 and Preparation Example 1 is that the usage ratio of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane is different, that is, the usage ratio of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane is 1:0.4, and the others are the same as Preparation Example 1.

[0070] Preparation Comparative Example 4

[0071] The difference between Preparation Example 4 and Preparation Example 1 is that in Preparation Example 4, an equal amount of Si-69 silane coupling agent is replaced by polytrifluoropropylmethylsiloxane, and the rest is the same as Preparation Example 1.

[0072] Preparation Comparative Example 5

[0073] The difference between Preparation Comparative Example 5 and Preparation Example 1 is that the silica aerogel prepared in step A3 is directly subjected to solvent replacement in 5 kg of ethanol, and after the solvent replacement is completed, it is dried at a temperature of 90° C. to obtain the silica aerogel, and the rest is the same as Preparation Example 1.

[0074] Example

[0075] Example 1

[0076] Example 1 discloses an aerogel thermal insulation coating, which is prepared by the following steps:

[0077] S1, adding 2.5kg of polyethylene glycol 3000 as polyethylene glycol, 1.8kg of isophorone diisocyanate as diisocyanate and 0.01kg of dibutyltin dioctanoate as catalyst into a reactor, heating to 95°C for reaction, controlling the stirring speed to 200r / min, stirring for reaction for 2h, and stopping the reaction when the cyanide-hydroxyl ratio in the system is 3.9:1 to obtain reactant A;

[0078] S2, add a chain extender consisting of 0.57kg dihydroxybutyric acid and 0.23kg butanediol to reactant A, cool to 70°C for reaction, stir at a speed of 200r / min, react for 1h, and stop the reaction when the cyanide-hydroxyl ratio in the system is 1.1:1 to obtain reactant B;

[0079] S3, add 0.14kg hydroxy fluorosilicone oil and 0.01kg polyethylene glycol glycidyl ether composed of adhesion promoter to reactant B, stir evenly, cool to 45 ° C, add 0.23kg triethylamine as the first neutralizer, stir and emulsify, stir at a stirring speed of 1000r / min, stir and react for 10min, then add 8kg water and continue to stir and emulsify, stir for 10min, to obtain reactant C;

[0080] S4, continue to add diethylamine as a second neutralizing agent to the reactant C, mix and stir, and stir for 5 minutes to obtain an aqueous polyurethane emulsion;

[0081] S5. Add 1.5 kg of silica aerogel prepared in Preparation Example 1 to the aqueous polyurethane emulsion prepared above, first stir at a high speed of 1000 r / min for 10 min, then stir at a low speed of 400 r / min for 20 min to obtain an aerogel thermal insulation coating.

[0082] Example 2-3

[0083] The difference between Example 2-3 and Example 1 is that the amount of raw materials used and the preparation conditions are different, and the source of the silica aerogel is also different, as shown in Table 2 below.

[0084] Table 2 Specific vegetation conditions and raw material usage of Examples 1-3

[0085]

[0086]

[0087] Example 4

[0088] The difference between Example 4 and Example 1 is that the usage ratio of the adhesion promoter is different. The usage of hydroxyfluorosilicone oil in Example 4 is 0.115 kg, and the usage of polyethylene glycol glycidyl ether is 0.035 kg. The rest is the same as Example 1.

[0089] Example 5

[0090] The difference between Example 5 and Example 1 is that an equal amount of polyethylene glycol glycidyl ether is replaced by hydroxyfluorosilicone oil, and the rest is the same as Example 1.

[0091] Embodiment 6-11

[0092] The difference between Examples 6-11 and Example 1 is that the sources of the silica aerogel are different, see Table 3 below for details.

[0093] Table 3 Sources of silica aerogels of Examples 6-11

[0094] Example Silica Aerogel Source Example 6 Preparation Comparative Example 1 Example 7 Preparation Comparative Example 2 Example 8 Preparation Comparative Example 3 Example 9 Preparation Comparative Example 4 Example 10 Preparation Comparative Example 5 Embodiment 11 Commercially available

[0095] Example 12

[0096] The difference between Example 12 and Example 1 is that the cyanide-hydroxyl ratio of the reactant A prepared in step S1 is 4.5:1, and the rest is the same as Example 1.

[0097] Embodiment 13

[0098] The difference between Example 13 and Example 1 is that the cyanide-hydroxyl ratio of the reactant B prepared in step S2 is 0.7:1, and the rest is the same as Example 1.

[0099] Embodiment 14

[0100] The difference between Example 14 and Example 1 is that after adding the silica aerogel in step S5, the stirring rate is controlled to 1000 r / min, and after stirring for 20 minutes, the stirring is stopped to obtain the aerogel thermal insulation coating. The rest is the same as Example 1.

[0101] Comparative Example

[0102] Comparative Example 1

[0103] The difference between Comparative Example 1 and Example 1 is that the silica aerogel is replaced by commercially available hollow glass microspheres in an equal amount, and the particle size of the hollow glass microspheres is 10-20 μm. The rest is the same as Example 1.

[0104] Comparative Example 2

[0105] The difference between Comparative Example 2 and Example 1 is that no adhesion promoter is added, and the other parts are the same as Example 2.

[0106] Performance testing

[0107] The performance of the aerogel thermal insulation coatings prepared in Examples 1-14 and Comparative Examples 1-2 was tested, and the specific test items are as follows:

[0108] (1) Thermal conductivity

[0109] According to GB / T 10297 "Hot-wire method for determination of thermal conductivity of non-metallic solid materials", the aerogel thermal insulation coating is applied to the surface of the test glass sheet, the coating thickness of the aerogel thermal insulation coating is 10 μm (the coating thickness in comparative example 1 is 20 μm, because the particle size of the hollow glass microspheres is large, the thickness of the test coating film is also correspondingly large), after drying at a temperature of 140°C for 20 minutes, the temperature is lowered to 25°C, and the thermal conductivity (unit: W / (m·K)) is tested, and the test results are detected and recorded;

[0110] (2) Light transmittance

[0111] The aerogel thermal insulation coating is applied to the surface of the test glass sheet, and the coating thickness of the aerogel thermal insulation coating is 10 μm (the coating thickness in comparative example 1 is 20 μm, and since the particle size of the hollow glass microspheres is relatively large, the thickness of the test coating film is also correspondingly large), and after drying at a temperature of 140° C. for 20 minutes, the temperature is lowered to 25° C., and a glass light transmittance tester is used. Based on the length direction of the test glass sheet, the left, middle, and right regions are selected for light transmittance (unit: %) test, and the test results are averaged and recorded;

[0112] (3) Adhesion

[0113] According to the test method in GB / T 5210-2006 "Adhesion Test of Colored Paint and Paint Pull-off Method", the aerogel thermal insulation coating is applied to the surface of the test glass sheet, and the coating thickness of the aerogel thermal insulation coating is 10 μm (the coating thickness in Comparative Example 1 is 20 μm. Since the particle size of the hollow glass microspheres is relatively large, the thickness of the test coating film is also relatively large). After drying at a temperature of 140°C for 20 minutes, the temperature is reduced to 25°C. After being placed for 2 hours, the adhesion is tested and recorded as the first adhesion (unit: MPa). The test glass sheet coated with the aerogel thermal insulation coating is placed in a UV weather resistance test box at a temperature of 85°C and a humidity of 85%. The test is carried out for 7 days. After the test, the temperature is reduced to 25°C, and the adhesion is tested and recorded as the second adhesion (unit: MPa). The test results are detected and recorded;

[0114] The following are the test data of thermal conductivity, light transmittance and adhesion of the aerogel thermal insulation coatings prepared in Examples 1-14 and Comparative Examples 1-2, see the table below for details.

[0115] Table 4 Performance test data of aerogel thermal insulation coatings prepared in Examples 1-14 and Comparative Examples 1-2

[0116]

[0117]

[0118] Combining Examples 1-3 and Examples 6-11, Comparative Example 1 and Table 4, it can be seen that the silica aerogel prepared by the preparation method of the present application is applied to aerogel thermal insulation coatings, and has good thermal insulation, and the thermal conductivity can be as low as 0.13W / (m·K), the transmittance is as high as 85.2%, and the adhesion can reach 3.21MPa. After the weather resistance test, the adhesion on the rear side can also be maintained at 3.2MPa, which is basically unchanged. In Examples 6-7, the optimal ratio of polyethylene glycol 800 and diethylene glycol was not used in the process of preparing the silica aerogel matrix, and the thermal conductivity of the aerogel thermal insulation coating obtained increased, indicating that the thermal insulation decreased and the adhesion also decreased slightly. This may be because the skeleton strength of the prepared silica aerogel is low, which makes the structure of the silica aerogel easy to shrink and crack; in the process of preparing the silica aerogel in Examples 8-10, Without using the optimal ratio of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane as the interfacial crosslinking agent, the thermal conductivity of the aerogel thermal insulation coating obtained is improved to 0.196W / (m·K), indicating that the thermal insulation is reduced, the light transmittance is reduced to 83.9%, and the adhesion is also significantly reduced, the adhesion is 2.84MPa, and the adhesion is reduced to 2.7MPa after the weather resistance test, indicating that the adhesion stability is significantly reduced. This may be because the use of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane has better dispersibility for the prepared silica aerogel, and can improve the light transmittance, adhesion and thermal insulation of the prepared aerogel thermal insulation coating. In Example 11, commercially available silica aerogel is used, and the various properties of the prepared aerogel thermal insulation coating are reduced. In Comparative Example 1, the silica aerogel is replaced with hollow glass microspheres. Although the coating thickness is greater than that of Example 1, the various properties are significantly reduced.

[0119] In combination with Examples 1-3 and Examples 4-5, Comparative Example 2 and Table 4, it can be seen that the use of the preferred ratio of hydroxyfluorosilicone oil and polyethylene glycol glycidyl ether in the present application as an adhesion promoter can better improve the adhesion and thermal insulation performance of the aerogel thermal insulation coating. In Example 4, the preferred ratio is used to improve the performance of the aerogel thermal insulation coating. In Example 5, only hydroxyfluorosilicone oil is added, and various properties are reduced. In Comparative Example 2, no adhesion promoter is added, and the adhesion of the aerogel thermal insulation coating is significantly reduced. The adhesion after weather resistance test is significantly reduced, and the thermal insulation and light transmittance are also slightly reduced.

[0120] It can be seen from Example 1 and Examples 12-14 and Table 4 that by using the step-by-step reaction preparation method of the present application and controlling the cyanide-hydroxyl ratio of reactant A and reactant B within a preferred range, the various properties of the aerogel thermal insulation coating can be improved.

[0121] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An aerogel thermal insulation coating, characterized in that: It is prepared from the following raw materials in parts by weight: 25-45 parts of polyethylene glycol 18-38 parts of diisocyanate Silica aerogel 15-30 parts Catalyst 0.1-0.3 parts Chain extender 8-16 parts Adhesion promoter 1.5-3.5 parts 3-6 parts of neutralizer 80-110 parts of water; The silica aerogel is prepared by the following steps: A1. Add 15-25 parts of ethyl orthosilicate to 30-50 parts of ethanol by weight, mix well, add 3-6 parts of water, control the temperature to 20-35°C, add 0.3-0.8 parts of hydrofluoric acid for hydrolysis, react for 10-20 minutes, and obtain a prepolymer; A2, adding 1-2 parts of ammonia water and 1.5-2.5 parts of polyethylene glycol 800 and diethylene glycol in a weight ratio of 1: (0.2-0.4) to the prepolymer, reacting for 20-40 minutes to obtain a silica aerogel matrix; A3. Add 10-20 parts of water to the prepared silica aerogel matrix, place it at a temperature of 55-65° C., let it stand for 6-12 hours, and then filter it; A4, adding 1-3 parts of Si-69 silane coupling agent and polytrifluoropropylmethylsiloxane in a dosage ratio of 1: (0.5-0.7) to the silica aerogel matrix prepared in step A3, stirring evenly, adding 50-70 parts of ethanol for solvent replacement, and then drying at normal pressure to obtain silica aerogel; The adhesion promoter is composed of hydroxy fluorosilicone oil and polyethylene glycol glycidyl ether in a dosage ratio of 1:(0.1-0.3).

2. The aerogel thermal insulation coating according to claim 1, characterized in that: The polyethylene glycol is one or a combination of polyethylene glycol 1000, polyethylene glycol 1500, polyethylene glycol 2000, and polyethylene glycol 3000.

3. The aerogel thermal insulation coating according to claim 1, characterized in that: The diisocyanate is isophorone diisocyanate and / or hexamethylene diisocyanate.

4. The aerogel thermal insulation coating according to claim 1, characterized in that: The chain extender is composed of dimethylol propionic acid and butanediol in a weight ratio of 1:(0.4-0.6).

5. The aerogel thermal insulation coating according to claim 1, characterized in that: The catalyst is any one of dibutyltin dilaurate and stannous octoate.

6. The aerogel thermal insulation coating according to claim 1, characterized in that: The neutralizer is composed of a first neutralizer and a second neutralizer in a dosage ratio of 1:(0.3-0.5), the first neutralizer is triethylamine and / or ammonia water, and the second neutralizer is diethylamine.

7. A method for preparing the aerogel thermal insulation coating according to claim 6, characterized in that: The method comprises the following preparation steps: S1, adding polyethylene glycol, diisocyanate and catalyst into a reaction device, heating to 95-120°C for reaction, and obtaining reactant A; S2, adding a chain extender to reactant A, cooling to 70-80°C for reaction, and obtaining reactant B; S3, adding an adhesion promoter to reactant B, stirring evenly, cooling to 45-60° C., adding a first neutralizer, stirring and emulsifying, and then adding water, stirring and emulsifying to obtain reactant C; S4, continue to add the second neutralizing agent to the reactant C and mix and stir to obtain an aqueous polyurethane emulsion; S5. Add silica aerogel to the aqueous polyurethane emulsion, and prepare the aerogel thermal insulation coating after stirring and dispersing.

8. The method for preparing an aerogel thermal insulation coating according to claim 7, characterized in that: In the step S1, the cyanide-hydroxyl ratio of the obtained reactant A is (3.9-4.1):1, and in the step S2, the cyanide-hydroxyl ratio of the obtained reactant B is (1.1-1.4):

1. In the step S5, after adding the silica aerogel, high-speed stirring is first performed at a speed of 1000-1500 r / min, and then low-speed stirring is performed at a speed of 400-600 r / min.

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