Aerogel modified reflective insulation MPC coating and preparation method thereof

Abstract

The invention belongs to the technical field of coatings, and particularly relates to an aerogel modified reflective insulation MPC coating and a preparation method thereof. The aerogel modified reflective thermal insulation MPC coating provided by the invention is prepared from the following raw materials in parts by weight: 60 to 74 parts of magnesia, 45 to 55 parts of phosphate, 6 to 8 parts of retarder, 31 to 92 parts of thermal insulation filler, 1 to 3 parts of functional additive, 1 to 5 parts of aerogel and 48 to 84 parts of water. The aerogel modified reflective heat insulation MPC coating has excellent reflective heat insulation performance, and also has good constructability and durability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coatings, and particularly relates to an aerogel modified reflective thermal insulation MPC coating and a preparation method thereof. BACKGROUND

[0002] At present, the demand for high-efficiency energy-saving materials in the fields of construction and industry is increasingly urgent. The transmission of solar radiation heat through the surface of the building envelope or equipment is an important factor leading to the increase of energy consumption. Although the traditional reflective thermal insulation coating can reflect part of the solar radiation, it generally has the problems of insufficient thermal insulation effect and single function. The main reason is that it relies on a single surface reflection mechanism, and has limited blocking ability for infrared band heat conduction. In addition, most of the traditional reflective thermal insulation coatings use organic resins as binders, which are prone to aging in high-temperature environments, have weak adhesion to inorganic substrates, and are difficult to meet the multiple performance requirements such as fireproofing, corrosion resistance, and environmental protection.

[0003] As a new inorganic cementitious system, magnesium phosphate cement (MPC) material has significant advantages: its water-based formula is environmentally friendly and non-toxic, and after solidification, it forms a chemical bond with substrates such as concrete and steel, with a bonding strength of more than 5 MPa, and excellent high-temperature resistance (can withstand temperatures above 1000℃). In humid or corrosive environments, it can form a dense magnesium phosphate salt protective layer to inhibit metal corrosion. However, the thermal insulation design of traditional MPC coatings mainly relies on porous fillers, which lack selective reflection ability for solar radiation, and their thermal conductivity is usually higher than 0.3 W / (m·K), making it difficult to meet the needs of demanding energy-saving scenarios. SUMMARY

[0004] Therefore, the purpose of the present application is to provide an aerogel modified reflective thermal insulation MPC coating and a preparation method thereof. The aerogel modified reflective thermal insulation MPC coating provided by the present application has excellent reflective thermal insulation performance, as well as good workability and durability.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: The present application provides an aerogel modified reflective thermal insulation MPC coating, which comprises the following raw materials by weight: magnesite 60-74 parts, phosphate 45-55 parts, retarder 6-8 parts, thermal insulation filler 31-92 parts, functional additive 1-3 parts, aerogel 1-5 parts, and water 48-84 parts.

[0006] Preferably, the aerogel is one or more of silica aerogel, alumina aerogel, and carbon aerogel.

[0007] Preferably, the particle size of the aerogel is 10-100 μm, and the aerogel is subjected to surface hydrophobic treatment.

[0008] Preferably, the modifying liquid used in the surface hydrophobic treatment comprises a solute and a solvent; the solute comprises methyltrimethoxysilane and / or gamma-aminopropyltriethoxysilane.

[0009] Preferably, the functional additive is at least one of a dispersant, a leveling agent and a defoaming agent; the dispersant comprises at least one of sodium hexametaphosphate, sodium polycarboxylate, polyvinyl alcohol and sodium silicate.

[0010] Preferably, the thermal insulation filler comprises one or more of rutile titanium dioxide, hollow glass microbeads and hollow ceramic microbeads.

[0011] Preferably, the retarder is composed of borax and disodium hydrogen phosphate dodecahydrate; the weight ratio of the borax and the disodium hydrogen phosphate dodecahydrate is 1-4:1.

[0012] Preferably, the phosphate is potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate.

[0013] Preferably, the magnesia is dead-burned magnesia obtained by high-temperature calcination of magnesite and / or magnesia obtained by high-temperature electric melting of magnesite.

[0014] The application further provides a preparation method of the aerogel modified reflective thermal insulation MPC coating. The magnesia, the phosphate, the retarder, the thermal insulation filler, the functional additive, the aerogel and water are mixed to obtain the aerogel modified reflective thermal insulation MPC coating.

[0015] The application provides an aerogel modified reflective thermal insulation MPC coating, which comprises the following raw materials in parts by weight: 60-74 parts of magnesia, 45-55 parts of phosphate, 6-8 parts of retarder, 31-92 parts of thermal insulation filler, 1-3 parts of functional additive, 1-5 parts of aerogel and 48-84 parts of water. DETAILED DESCRIPTION

[0016] The application provides an aerogel modified reflective thermal insulation MPC coating, which comprises the following raw materials in parts by weight: 60-74 parts of magnesia, 45-55 parts of phosphate, 6-8 parts of retarder, 31-92 parts of thermal insulation filler, 1-3 parts of functional additive, 1-5 parts of aerogel and 48-84 parts of water.

[0017] Unless otherwise specified, the source of the raw materials used in the present application is not particularly limited, and commercially available products known to those skilled in the art can be used.

[0018] The raw materials of the aerogel modified reflective thermal insulation MPC coating provided by the present application include 60-74 parts of magnesia, another embodiment is 65-70 parts, and a specific embodiment is 68-70 parts by weight.

[0019] As an embodiment, the magnesia is dead-burned magnesia obtained by high-temperature calcination of magnesite and / or magnesia obtained by high-temperature electric smelting of magnesite, and a specific embodiment is dead-burned magnesia obtained by high-temperature calcination of magnesite; the temperature of the high-temperature calcination is 1700-1800°C, and a specific embodiment is 1750°C; the holding time is 6-8 h, and a specific embodiment is 7 h; the high-temperature calcination is carried out in an air atmosphere; the temperature of the high-temperature electric smelting is 2800-3000°C, and a specific embodiment is 2850-2900°C; the holding time is 1.5-2.5 h, and a specific embodiment is 2 h; the high-temperature electric smelting is carried out in an inert atmosphere; the inert atmosphere is argon; and the particle size of the magnesia is 1-50 μm, and the average particle size is 46.65 μm. The magnesia treated by high-temperature calcination or high-temperature electric smelting has the characteristics of high purity, high density, high temperature resistance, and alkali resistance.

[0020] The raw materials of the aerogel modified reflective thermal insulation MPC coating provided by the present application include 45-55 parts of phosphate, another embodiment is 48-53 parts, and a specific embodiment is 50-53 parts per 1 part of magnesia by weight.

[0021] As an embodiment, the phosphate is potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate, and a specific embodiment is potassium dihydrogen phosphate; the molar ratio of the magnesia to the phosphate is 3-5:1, and a specific embodiment is 4-5:1; this ratio can ensure the reactivity and stability of the gel system.

[0022] The raw materials of the aerogel modified reflective thermal insulation MPC coating provided by the present application include 6-8 parts of a retarder, another embodiment is 6-7 parts, and a specific embodiment is 6.5-7 parts per 1 part of magnesia by weight.

[0023] As an embodiment, the retarder consists of borax and disodium hydrogen phosphate dodecahydrate; the weight ratio of the borax to the disodium hydrogen phosphate dodecahydrate is 1-4:1, and a specific embodiment is 2-4:1; the mass of the coagulant accounts for 8-12% of the mass of the magnesia, and a specific embodiment is 9-12%, which can effectively adjust the setting time of the coating and meet the operation requirements.

[0024] The raw materials of the aerogel modified reflective thermal insulation MPC coating provided by the present application include 31-92 parts of thermal insulation fillers, another embodiment is 40-70 parts, and a specific embodiment is 45-60 parts, based on 1 part by weight of magnesia.

[0025] As an embodiment, the thermal insulation fillers include one or more of rutile titanium dioxide, hollow glass microspheres and hollow ceramic microspheres, and a specific embodiment is rutile titanium dioxide; the particle size of the thermal insulation fillers is 10-100 μm, and a specific embodiment is 20-60 μm. The present application enhances the reflective thermal insulation effect of the coating through the synergistic effect between the light reflection characteristics of titanium dioxide and the nano-porous structure of aerogel.

[0026] The raw materials of the aerogel modified reflective thermal insulation MPC coating provided by the present application include 1-3 parts of functional additives, another embodiment is 1-2.5 parts, and a specific embodiment is 2-2.5 parts, based on 1 part by weight of magnesia.

[0027] As an embodiment, the functional additives are at least one of dispersants, leveling agents and defoaming agents, and a specific embodiment is a dispersant; the dispersant includes at least one of sodium hexametaphosphate, sodium polycarboxylate, polyvinyl alcohol and sodium silicate, and a specific embodiment is sodium hexametaphosphate; the leveling agent includes silicone leveling agent and / or acrylate leveling agent, and a specific embodiment is silicone leveling agent; the defoaming agent includes silicone defoaming agent and / or polyether defoaming agent, and a specific embodiment is silicone defoaming agent. The dispersant is used to improve the dispersibility of the raw materials and the construction performance of the coating.

[0028] The raw materials of the aerogel modified reflective thermal insulation MPC coating provided by the present application include 1-5 parts of aerogel, another embodiment is 2-4 parts, and a specific embodiment is 3-4 parts, based on 1 part by weight of magnesia.

[0029] As an embodiment, the aerogel is one or more of silica aerogel, alumina aerogel and carbon aerogel, and in particular embodiments, the aerogel is silica aerogel or carbon aerogel; the particle size of the aerogel is 10-100 μm, and in particular embodiments, 20-65 μm, and the aerogel is subjected to surface hydrophobic treatment; the modifying liquid used in the surface hydrophobic treatment comprises a solute and a solvent; the solute comprises methyltrimethoxysilane and / or γ-aminopropyltriethoxysilane, and in particular embodiments, methyltrimethoxysilane; the solvent comprises ethanol and water; the volume ratio of the ethanol to water is 2-4:1, and in particular embodiments, 3:1; the mass concentration of the solute in the modifying liquid used in the surface hydrophobic treatment is 5-8%, and in particular embodiments, 6%; the specific steps of the surface hydrophobic treatment are as follows: after the aerogel is subjected to drying pretreatment, it is placed in the modifying liquid used in the surface hydrophobic treatment, and is subjected to modification under the conditions of water bath and stirring, followed by solid-liquid separation, washing and drying of the obtained solid to obtain the aerogel subjected to surface hydrophobic treatment; the drying pretreatment is vacuum drying; the vacuum degree of the vacuum drying is 0.08-0.1 MPa, and in particular embodiments, 0.09 MPa; the temperature of the drying pretreatment is 70-90 °C, and in particular embodiments, 80 °C, and the time is 1-3 h, and in particular embodiments, 2 h; the mass ratio of the aerogel to the modifying liquid used in the surface hydrophobic treatment is 1:8-10, and in particular embodiments, 1:9; the stirring rate is 200-400 rpm, and in particular embodiments, 300 rpm; the modification temperature is 50-60 °C, and in particular embodiments, 55 °C; the modification time is 2-3 h, and in particular embodiments, 2.5 h; the solid-liquid separation is centrifugal separation; the centrifugal speed of the centrifugal separation is 3000-5000 rpm, and in particular embodiments, 4000 rpm, and the time is 5-15 min, and in particular embodiments, 10 min; the reagent used in the washing is ethanol; the drying temperature is 90-110 °C, and in particular embodiments, 100 °C, and the time is 3-4 h, and in particular embodiments, 3.5 h; the water content of the aerogel subjected to surface hydrophobic treatment is ≤5%, and in particular embodiments, 2%, which can improve the dispersibility and water resistance of the aerogel in the coating. The surface hydrophobic treatment can enhance the durability of the coating, does not completely mix with water, and can maintain the heat preservation and insulation effect of the aerogel for a long time.

[0030] As a nano-porous material (porosity > 80%, thermal conductivity as low as 0.013 W / (m·K)), aerogel can effectively scatter solar infrared radiation (800~2500nm) through its unique nano-pore structure, and block the conduction path by limiting the thermal motion of air molecules. By introducing aerogel into the MPC system, the coating can achieve a synergistic thermal insulation effect of "reflection-barrier": the chemical bond between the silicon hydroxyl group on the surface of the aerogel and the hydration product of MPC improves the density and flexibility of the coating; the high scattering characteristics of aerogel to near-infrared light combined with the addition of infrared reflective pigments (such as iron-titanium oxides, hollow ceramic microbeads) in the MPC matrix can increase the solar radiation reflectivity to more than 85%, while reducing the thermal conductivity of the coating to less than 0.08 W / (m·K). In addition, the hydrophobicity of aerogel and the alkaline environment of MPC can improve the weather resistance of the coating, and the fast setting characteristics (20~30min initial setting) of MPC can meet the rapid construction requirements of engineering.

[0031] In the related art, the composite research of aerogel and reflective thermal insulation function is mostly focused on organic-based coatings, which has the defects of poor high-temperature resistance and insufficient compatibility with inorganic substrates; and the aerogel modification research for MPC base has not involved the design of solar radiation reflection function, and has not solved the dispersion problem of aerogel in the water-based system. The present application innovatively constructs a multifunctional coating system with high-efficiency reflective thermal insulation, strong adhesion, high-temperature resistance and corrosion resistance by hydrophobic treatment of aerogel, hydroxylation of its surface, and compounding with thermal insulation fillers and optimizing the MPC base formula, so that it is suitable for high-temperature and high-radiation scenes such as building roof, industrial steel structure and new energy equipment.

[0032] The raw materials of the aerogel modified reflective thermal insulation MPC coating provided by the present application include 48~84 parts of water based on 1 part by weight of magnesia, and another embodiment is 56~80 parts, and in a specific embodiment, 60~75 parts.

[0033] The present application also provides a preparation method of the aerogel modified reflective thermal insulation MPC coating described in the above technical solution, which includes the following steps: Mixing magnesia, phosphate, retarder, thermal insulation filler, functional additive, aerogel and water to obtain the aerogel modified reflective thermal insulation MPC coating.

[0034] As an implementation form, the mixing is: mixing water and functional adjuvant, first stirring, adding aerogel and thermal insulation filler, second stirring, and then adding magnesia, phosphate and retarder, and sequentially slow stirring and fast stirring, or mixing water, functional adjuvant, aerogel and thermal insulation filler, third stirring, and then adding magnesia, phosphate and retarder, and sequentially slow stirring and fast stirring; the first stirring is at a speed of 500-800 rpm, specifically 600 rpm, and the time is 1-2 min, specifically 1 min; the second stirring is at a speed of 500-800 rpm, specifically 600 rpm, and the time is 3-5 min, specifically 3 min; the third stirring is at a speed of 500-1000 rpm, specifically 500-600 rpm, and the time is 2-5 min, specifically 2-4 min; the slow stirring is at a speed of 500-800 rpm, specifically 500-600 rpm, and the time is 30 s-2 min, specifically 30 s; and the fast stirring is at a speed of 800-1000 rpm, specifically 1000 rpm, and the time is 1-2 min, specifically 60 s.

[0035] As an implementation form, before the mixing, the method further comprises: crushing the phosphate and the retarder into powder and sieving; the crushing device is a pulverizer; and the sieving is performed by using a 100-mesh sieve.

[0036] The aerogel modified reflective thermal insulation MPC coating disclosed in the application comprises magnesia, phosphate, retarder, thermal insulation filler, functional adjuvant, aerogel and water, the magnesia is high-temperature calcined dead-burned magnesia or electrically fused magnesia, the phosphate is potassium dihydrogen phosphate or ammonium dihydrogen phosphate, and the molar ratio of the two is 3-5:1; the aerogel is modified to be hydrophobic, cooperates with the thermal insulation fillers such as rutile titanium dioxide and hollow glass microspheres, and builds a "reflection-barrier" dual thermal insulation mechanism. The coating mixture is uniformly dispersed by the stirring process, is suitable for manual brushing and mechanical spraying construction, is rapidly cured into a film at room temperature, and has a dense microstructure and a significant reflective thermal insulation effect. The coating uses water as a dispersion medium, is environmentally friendly and pollution-free, has the characteristics of fast hardening, early strength, weather resistance and durability, is especially suitable for reflective thermal insulation and protection of high-temperature outdoor scenes such as building outer walls and industrial equipment, effectively solves the problems of insufficient thermal insulation efficiency and poor construction performance of traditional coatings, and has significant technical progress and application value.

[0037] The technical solutions in the application will be described clearly and completely in combination with the embodiments in the application, but they should not be understood as limitations on the protection scope of the application.

[0038] Example 1 The following raw material components are included by weight parts: 65 parts of magnesia (dead burned magnesia after calcination of magnesite ore at a high temperature of 1750 °C in an air atmosphere for 7 h, with a particle size of 1-50 μm and an average particle size of 46.65 μm), 48 parts of potassium dihydrogen phosphate, 5 parts of borax, 2 parts of disodium hydrogen phosphate dodecahydrate, 25 parts of rutile titanium dioxide (with a particle size of 20-60 μm), 6 parts of hollow glass microbeads (with a particle size of 20-60 μm), 1 part of silica aerogel (with a particle size of 20-65 μm), 2 parts of sodium hexametaphosphate, and 56 parts of deionized water; After the borax, disodium hydrogen phosphate dodecahydrate, and sodium hexametaphosphate are all crushed into powder using a pulverizer and passed through a 100-mesh sieve, the rutile titanium dioxide, hollow glass microbeads, and silica aerogel are added to the deionized water, which is stirred at 600 rpm for 4 min until they are uniformly dispersed. Then, the magnesia, potassium dihydrogen phosphate, borax, and disodium hydrogen phosphate dodecahydrate are added, and the mixture is first stirred at 500 rpm for 30 s at a slow speed and then stirred at 1000 rpm for 60 s at a fast speed to obtain the aerogel-modified reflective thermal insulation MPC coating.

[0039] Example 2 The following raw material components are included by weight parts: 70 parts of magnesia (dead burned magnesia after calcination of magnesite ore at a high temperature of 1750 °C in an air atmosphere for 7 h, with a particle size of 1-50 μm and an average particle size of 46.65 μm), 52 parts of potassium dihydrogen phosphate, 6 parts of borax, 2 parts of disodium hydrogen phosphate dodecahydrate, 28 parts of rutile titanium dioxide (with a particle size of 20-60 μm), 7 parts of hollow ceramic microbeads (with a particle size of 20-60 μm), 2 parts of silica aerogel (with a particle size of 20-65 μm), 1.5 parts of sodium polycarboxylate, and 63 parts of deionized water; After the borax, disodium hydrogen phosphate dodecahydrate, and potassium dihydrogen phosphate are all crushed into powder using a pulverizer and passed through a 100-mesh sieve, the deionized water is mixed with the sodium polycarboxylate and stirred at 600 rpm for 1 min. Then, the titanium dioxide, ceramic microbeads, and silica aerogel are added and stirred at 600 rpm for 3 min. Finally, the magnesia, potassium dihydrogen phosphate, and retarder are added, and the mixture is first stirred at 500 rpm for 30 s at a slow speed and then stirred at 1000 rpm for 60 s at a fast speed to obtain the aerogel-modified reflective thermal insulation MPC coating.

[0040] Example 3 The following raw material components are included by weight parts: Magnesia (dead burned magnesia which is calcined at 1750 ℃ for 7 h in air atmosphere, particle size is 1-50 μm, average particle size is 46.65 μm) 68 parts, potassium dihydrogen phosphate 50 parts, borax 5 parts, disodium hydrogen phosphate dodecahydrate 1.5 parts, rutile titanium dioxide (particle size is 20-60 μm) 30 parts, silica aerogel (particle size is 20-65 μm) 4 parts, organic silicon leveling agent 1 part, sodium hexametaphosphate 1 part, deionized water 68 parts; The borax, disodium hydrogen phosphate dodecahydrate, sodium hexametaphosphate, potassium dihydrogen phosphate are all crushed into powder by a pulverizer and passed through a 100 mesh sieve, the leveling agent, sodium hexametaphosphate, rutile titanium dioxide, silica aerogel are added to the deionized water, stirred at 600 rpm for 4 min until no agglomeration, then the magnesia, potassium dihydrogen phosphate, retarder are added, first stirred slowly at 500 rpm for 30 s, then stirred quickly at 1000 rpm for 60 s, to obtain the aerogel modified reflective thermal insulation MPC coating.

[0041] Example 4 The following raw material components are included by weight parts: Magnesia (dead burned magnesia which is calcined at 1750 ℃ for 7 h in air atmosphere, particle size is 1-50 μm, average particle size is 46.65 μm) 68 parts, potassium dihydrogen phosphate 50 parts, borax 5 parts, disodium hydrogen phosphate dodecahydrate 1.5 parts, rutile titanium dioxide (particle size is 20-60 μm) 30 parts, silica aerogel (particle size is 20-65 μm) 4 parts, organic silicon leveling agent 1 part, sodium hexametaphosphate 1 part, deionized water 68 parts; The borax, disodium hydrogen phosphate dodecahydrate, potassium dihydrogen phosphate are all crushed into powder by a pulverizer and passed through a 100 mesh sieve, the deionized water is mixed with sodium silicate, then the titanium dioxide, hollow ceramic microbeads, carbon aerogel are added, stirred at 600 rpm for 3 min, then the magnesia, potassium dihydrogen phosphate, retarder are added, first stirred slowly at 500 rpm for 30 s, then stirred quickly at 1000 rpm for 60 s, to obtain the aerogel modified reflective thermal insulation MPC coating.

[0042] Example 5 The following raw material components are included by weight parts: 68 parts of magnesia (burnt magnesia after calcination of magnesite ore in air atmosphere at a high temperature of 1750 °C for 7 h, with a particle size of 1-50 pm and an average particle size of 46.65 pm), 50 parts of potassium dihydrogen phosphate, 5 parts of borax, 1.5 parts of disodium hydrogen phosphate dodecahydrate, 30 parts of rutile titanium dioxide (with a particle size of 20-60 pm), 5 parts of silica aerogel (with a particle size of 20-65 pm) after surface hydrophobic treatment, 1 part of silicone antifoaming agent, 1 part of sodium hexametaphosphate, and 64 parts of deionized water; the surface hydrophobic treatment is as follows: the aerogel is vacuum dried for pretreatment at a vacuum degree of 0.09 MPa and a temperature of 80 °C for 2 h, then placed in a modification liquid (solvent: ethanol and water in a volume ratio of 3:1) with a mass concentration of 6% of methyltrimethoxysilane, the mass ratio of the aerogel to the modification liquid is 1:9, and the modification is carried out at 55 °C water bath and 300 rpm stirring for 2.5 h, then centrifuged at 4000 rpm for 10 min, and the obtained solid is washed with ethanol and dried at 100 °C for 3.5 h; the water content of the aerogel after surface hydrophobic treatment is 2%; The borax, disodium hydrogen phosphate dodecahydrate, sodium hexametaphosphate, and potassium dihydrogen phosphate are all crushed into powder with a powder mill and passed through a 100 mesh sieve, the deionized water is added with the antifoaming agent, sodium hexametaphosphate, rutile titanium dioxide, and silica aerogel after surface hydrophobic treatment, stirred at 600 rpm for 4 min until no agglomeration, then added with the magnesia, potassium dihydrogen phosphate, and retarder, first stirred slowly at 500 rpm for 30 s, then stirred quickly at 1000 rpm for 60 s, to obtain the aerogel modified reflective thermal insulation MPC coating.

[0043] Comparative Example 1 The difference from Example 1 is that no silica aerogel is added in Comparative Example 1.

[0044] Performance Test The aerogel modified reflective thermal insulation MPC coatings prepared in Examples 1-5 are sprayed on the surface of steel plates to form hardened coatings, and the performance of the hardened coatings is tested, and the specific test methods are as follows: 1. Sample Preparation The prepared coating is sprayed on an aluminum alloy plate or a Q235 steel plate, and the surface of the metal plate is treated as follows: first, degreasing treatment is performed using a sodium hydroxide solution (5 wt% concentration), then the surface is rinsed with clean water to ensure that the surface is clean; check whether there is rust on the surface of the metal plate. If so, the rusty metal plate is immersed in a dilute sulfuric acid solution (5 wt% concentration) for rust removal treatment, and then rinsed clean with clean water; finally, transverse and longitudinal polishing (150 mesh sandpaper) is performed respectively to increase the roughness of the surface of the metal plate. After 7 days of curing, the coating is tested.

[0045] 2. Hardness and Adhesion Test The hardness and adhesion of the coating were tested according to standards GB / T 6739-2006 and GB / T9286-1998, and the hardness grades from high to low were 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, B, 2B; the adhesion grades were 0 level without falling off, 1 level with falling off area less than 5%, 2 level with falling off area less than 15%, 3 level with falling off area less than 35%, and 4 level with falling off area less than 65%.

[0046] 3. Bonding strength test According to JGJ / T70-2009, the bonding strength between the steel plate and the coating at 7d age under normal temperature conditions was tested. A silica gel mold with an inner size of 40 mm x 40 mm x 6 mm was used to cast the coating neat slurry block at the center position of the Q235 steel plate (200 mm x 100 mm x 1 mm), and the slurry block was cured in a room temperature atmosphere. Before reaching the required age, a 40 mm square iron block was bonded to the slurry block using epoxy resin glue, and after the epoxy resin glue was completely cured, the forward tensile bonding strength test was performed.

[0047] 4. Reflective thermal insulation performance test According to standard JG / T 235-2008, a white foam box with a thermal conductivity of about 0.035 W / (m·K) was used as a heat preservation box to isolate the heat exchange of the external environment by its low thermal conductivity. A rectangular notch with a size of 150 mm x 70 mm was provided at the top of the heat preservation box. The sample plate to be tested was covered above the notch, and the initial temperature of the coating was maintained at about 25℃. The thermocouple of the surface thermometer was fixed at the center position of the back of the sample plate using heat-resistant adhesive tape, ensuring that the thermocouple was in close contact with the sample plate, to continuously record the temperature changes on the back. A 300 W infrared lamp was used as a heat source to vertically irradiate the sample plate, and the distance between the lamp and the sample plate was fixed at 30 cm. During the experiment, the back temperature data of the sample plate was automatically collected every 1 min, and the temperature was recorded when the back temperature of the sample plate and the internal temperature of the heat preservation box reached a stable state, and the heat insulation temperature difference was compared with the self-spraying black sample plate.

[0048] According to the requirements of JG / T 235-2014 standard, a Lambda950 type ultraviolet visible near infrared spectrophotometer was used to measure the solar reflectance and near infrared reflectance of the sample in the wavelength range of 300~2500 nm. First, the solar reflectance spectrum was generated, and the spectral reflectance value p(λ) of the sample at each wavelength was obtained, then the solar reflectance p was calculated by formula (1), and the near infrared reflectance p was calculated by formula (2) NIR .

[0049] (1) wherein ρ is the solar reflectance of the sample; ρ0(λ) is the spectral reflectance of the standard white board; ρ(λ) is the spectral reflectance of the sample; S λ is the relative spectral distribution of solar radiation (see JG / T 235-2014 Table A.1); Δλ is the wavelength interval (mm).

[0050] (2) wherein ρ NIR is the near-infrared reflectance of the sample; ρ0(λ) is the spectral reflectance of the standard white board; ρ(λ) is the spectral reflectance of the sample; S λ is the relative spectral distribution of solar radiation (see JG / T 235-2014 Table A.2); Δλ is the wavelength interval (nm).

[0051] The test results are shown in Table 1.

[0052] Table 1 Performance of aerogel-modified reflective thermal insulation MPC coating hardened coating

[0053] As can be seen from Table 1, in the aerogel-modified reflective thermal insulation MPC coating, the addition of aerogel can significantly improve the thermal insulation performance and solar reflectivity of the coating, and the coating can maintain good mechanical properties such as hardness and adhesion. Aerogel is a key component for optimizing the reflective thermal insulation effect of such coatings. After the surface of the aerogel is treated to be hydrophobic, the improvement of the thermal insulation performance and solar reflectivity of the coating is more prominent. Compared with the aerogel that is not modified to be hydrophobic, the hydrophobic modification can further strengthen the reflective thermal insulation capacity of the coating. Within a reasonable range, increasing the amount of aerogel helps to further improve the thermal insulation performance of the coating, and the amount and the thermal insulation effect show a positive correlation trend (the amount needs to be controlled within the suitable range of the system).

[0054] Although the above embodiments have made a detailed description of the present application, it is only a part of the embodiments of the present application but not all the embodiments. Other embodiments can be obtained according to the present embodiments without creativity, and these embodiments all belong to the protection scope of the present application.

Claims

1. An aerogel-modified reflective thermal insulation MPC coating, characterized in that, The composition comprises the following raw materials by weight: magnesia 60-74 parts, phosphate 45-55 parts, retarder 6-8 parts, thermal insulation filler 31-92 parts, functional additive 1-3 parts, aerogel 1-5 parts, and water 48-84 parts.

2. The aerogel-modified reflective, thermally insulating MPC coating of claim 1, wherein, The aerogel is one or more of silica aerogel, alumina aerogel and carbon aerogel.

3. The aerogel-modified reflective, thermally insulating MPC coating of claim 2, wherein, The aerogel has a particle size of 10-100 μm, and the aerogel is subjected to surface hydrophobic treatment.

4. The aerogel-modified reflective, thermally insulating MPC coating of claim 3, wherein, The modifying liquid used in the surface hydrophobic treatment comprises a solute and a solvent; the solute comprises methyltrimethoxysilane and / or γ-aminopropyltriethoxysilane.

5. The aerogel modified reflective radiant barrier MPC coating of claim 1, wherein, The functional additive is at least one of dispersant, leveling agent and defoaming agent; the dispersant comprises at least one of sodium hexametaphosphate, polycarboxylic acid sodium salt, polyvinyl alcohol and sodium silicate.

6. The aerogel modified reflective radiant barrier MPC coating of claim 1, wherein, The thermal insulation filler comprises one or more of rutile titanium dioxide, hollow glass microbeads and hollow ceramic microbeads.

7. The aerogel modified reflective radiant barrier MPC coating of claim 1, wherein, The retarder is composed of borax and disodium hydrogen phosphate dodecahydrate; the weight ratio of the borax and the disodium hydrogen phosphate dodecahydrate is 1-4:

1.

8. The aerogel modified reflective radiant barrier MPC coating of claim 1, wherein, The phosphate is potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate.

9. The aerogel modified reflective radiant barrier MPC coating of claim 1, wherein, The magnesia is dead-burned magnesia obtained by high-temperature calcination of magnesite and / or magnesia obtained by high-temperature electric melting of magnesite.

10. The method of making the aerogel-modified reflective thermal insulation MPC coating of any one of claims 1-9, characterized in that, The method comprises the following steps: Mixing magnesia, phosphate, retarder, thermal insulation filler, functional additive, aerogel and water to obtain the aerogel modified reflective thermal insulation MPC coating.

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