The Application Of SiO₂ Aerogel In Reflective Insulation Coating

Building energy consumption accounts for about one-third of China's total energy consumption.Improving the thermal insulation performance of building maintenance structures is one of the important measures for building energy conservation.Due to the excellent thermal insulation performance of exterior wall reflective insulation coatings It can reduce the cooling energy consumption of buildings,so it has been used in some areas in the south of China,but it has not been used in the north.In order to adapt to the hot summer and cold winter climate in North China,it is necessary to further improve the thermal insulation performance of the reflective thermal insulation coating on the premise of ensuring the solar reflectance of the coating.SiO₂ aerogel is a super insulation material with high porosity and low thermal conductivity.Adding SiO₂ aerogel to reflective insulation coatings can improve the thermal insulation performance of the coatings.However,the amount of aerogel in the reflective thermal insulation coating is relatively high at present?4?5%is the least amount of SiO₂?;at the same time,SiO₂ aerogels are hydrophobic substances,which are prone to agglomeration in water-based coatings.Therefore,the purpose of this study is to improve the dispersibility of SiO₂ aerogels in reflective insulation coatings,reduce the amount of SiO₂aerogels,and thus reduce the cost of reflective insulation coatings,and promote their future promotion and application.First study the dispersibility of SiO₂ aerogel in aqueous solution,explore the type and amount of dispersant,the amount of stabilizer,the amount of wetting agent,the amount of SiO₂ aerogel,dispersion method,dispersion time,p H of the value on the dispersion properties of SiO₂ aerogel.The experiment confirmed that:when the p H is about 7.5,the dispersant1124 content is 1.5%,the SiO₂ aerogel content is 1%,the wetting agent PE-100 content is0.75%,and the stabilizer MP-3000S The blending amount is 1.5%,and the high-speed homogenizer is used for high-speed dispersion for 10 minutes?the rotation speed is 10000r/min?to obtain a SiO₂ aerogel slurry with good dispersion effect.Its light transmittance is15.3%.After one month,the SiO₂ aerogels The percentage of the settling volume of the glue slurry is 40.2%,the zeta potential value is-20.68m V,and the average particle size is about 42.57nm.The optimal ratio of pigments,fillers and film-forming materials was determined by orthogonal experiment.The effects of SiO₂ aerogel size and film thickness on the reflective and thermal insulation properties of the coatings were studied.Finally,the basic properties of the coatings were tested.When the dosage of silicone acrylic emulsion is 30%,the reflective and thermal insulation properties of coatings are the best.When talcum powder 7%,heavy calcium 19%,hollow glass beads 9%,rutile titanium dioxide 10%,when the SiO₂ aerogel dosage is 1%,the solar reflectance of the coating is as high as 91%,the thermal conductivity is as low as 0.065W/?m×k?,and the heat insulation temperature difference can reach 15.8?.When the film thickness of the coating is 600?m,its solar reflectivity and thermal conductivity can achieve the best effect.The temperature difference of self-made SiO₂ reflective thermal insulation coating is significantly higher than that of commercial coating.All properties of the coating have reached the requirements of relevant national standards.