Silica Aerogel Plays An Important Role In The Preparation Of Thermal Insulation Coating Fabrics


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Silica Aerogel Plays An Important Role In The Preparation Of Thermal Insulation Coating Fabrics

  • Categories:NEWS
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  • Time of issue:2021-06-18 15:43

Silica Aerogel Plays An Important Role In The Preparation Of Thermal Insulation Coating Fabrics

Thermal insulation coating fabric is a layer of thermal insulation coating on the surface of the fabric. By blocking, reflecting or radiating solar energy, it can reduce the internal temperature of the fabric covering and reduce energy consumption. It has a wide range of applications in the textile industry prospect.


According to the thermal insulation mechanism, fabric thermal insulation coatings can be divided into three types: barrier type, reflective type and radiation type. Barrier-type thermal insulation coating is a passive cooling coating that achieves heat insulation through the impedance effect of heat transfer. The thermal insulation mechanism is relatively simple. Generally, a composition with low thermal conductivity is used or a coating film with extremely low thermal conductivity is introduced. Air, in order to obtain a good thermal insulation effect, usually has the characteristics of relatively small bulk density, low thermal conductivity, and small dielectric constant. Reflective thermal insulation coatings isolate sunlight energy in the form of reflection. Commonly used reflective materials include ceramic powder, aluminum powder, titanium dioxide and ATO (antimony-doped tin dioxide) powder.


Common barrier-type fabric thermal insulation coating agents are divided into chemical structures, mainly polyvinyl chloride (PVC), polyacrylate (PA), polyurethane (PU), silicone, rubber emulsion and polytetrafluoroethylene Ethylene, among which PA and PU are used more; according to the use medium, it can be divided into two types: solvent type and water dispersion type.


As an amorphous nanoporous material, SiO2 aerogel has a controllable structure and a continuous three-dimensional network structure. And its density is adjustable between 3~500mg/cm3, it is the lowest density solid material in the world, the porosity can reach 80%~99.8%, the pore size is between 1~100nm, and the specific surface area can be as high as 1000m2/ g. Due to the unique nanoporous structure, its thermal conductivity is extremely low, and the thermal conductivity is as low as 0.017W/(m•K) at room temperature and pressure, which is the solid material with the lowest thermal conductivity currently known. Since the structural units constituting the aerogel skeleton are smaller than the visible light wavelength, it also has better light transmission properties. At the same time, it is an inorganic material with non-combustible or flame-retardant effect, and has a wide range of application prospects in the field of thermal insulation.


According to statistics, in recent years, the global aerogel market has a compound annual growth rate of 36.4%, while the domestic aerogel market has a compound annual growth rate of 61.1%. Its application in thermal insulation fabrics can not only reduce the weight of thermal protective clothing, make it lighter and thinner, but also greatly reduce work loss during use.


For example, SiO2 aerogel can be added to PA or PU adhesives in a certain proportion to prepare a thermal insulation coating agent, and the cotton fabric can be directly coated, and then dried, baked and other processes can be achieved. Preparation of SiO2 aerogel thermal insulation coating fabric. Compared with the original fabric, the thermal insulation performance of the coated fabric with SiO2 aerogel is significantly improved, and when the amount of aerogel in the coating agent is less than 10%, the thermal insulation effect of the fabric increases with the amount of SiO2 aerogel. The increase gradually becomes better.


In addition, glass fiber SiO2 aerogel felt can also be selected as the material of the fabric heat insulation layer. Its thermal protection performance is greater than 60, and it can withstand high temperature flame burning at 450 ℃ for 50s, which significantly improves the thermal protection performance of the fabric, which can resist such as fire fighting. The instantaneous high temperature.


SiO2 aerogel has the characteristics of high porosity and low thermal conductivity, making it a new type of super thermal insulation material. However, the flexibility and integrity of SiO2 aerogels are poor, and the thermal conductivity of aerogels dried at room temperature rises rapidly at high temperatures, which greatly limits the application of SiO2 aerogels. In recent years, the SiO2 aerogel composite heat insulation material prepared by in-situ sol-gel method and compression molding method has improved its toughness, integrity and high-temperature heat insulation performance to a certain extent, making SiO2 aerogel As a separate block insulation material becomes possible.