Fumed silica, also known as fumed silica, molecular formula: SiO2, is a white powder, porous, non-toxic, tasteless and pollution-free. It is a nano-powder material gradually recognized by people. At present, fumed silica has been widely used in silicone rubber, adhesives, ink coatings, resin composite materials and other fields.
With the development of science and technology and the expansion of downstream application fields, this kind of inorganic nanomaterials called "industrial monosodium glutamate" still has unlimited potential in the industry application prospects.
In recent years, the state has vigorously promoted the promotion and application of green energy-saving buildings and industrial energy-saving materials. In the thermal insulation industry, vacuum insulation boards with vacuum and porous materials as the core material have become a new hot product.
Vacuum insulation board (also known as VIP board) can effectively avoid heat transfer caused by air convection, so the thermal conductivity can be greatly reduced, less than 0.035w / (㎡.k), and does not contain any ODS materials, which is environmentally friendly and efficient. Energy-saving features are currently the world's most advanced high-efficiency thermal insulation materials. At present, it is mainly used for thermal insulation, such as household refrigerators, yacht refrigerators, mini refrigerators, car refrigerators, deep-freeze freezers, electric water heaters, vending machines, freezers, refrigerated containers, building wall insulation and LNG storage and transportation.
The vacuum insulation board is generally composed of three parts: core material, diaphragm and getter (drying agent). In the vacuum insulation board, the choice of core material is the key factor that determines the performance of the vacuum insulation board.
There are many choices of core materials for vacuum insulation boards, including glass wool, micro silicon powder, aerogel, fumed silica, and so on. At present, due to cost and other factors, the use of glass wool, micro-silica powder, etc. as the core material generally has a short shelf life, unstable production quality, and serious heat loss during edge sealing. And because of its unique characteristics, fumed silica is very suitable for preparing nanomaterials for vacuum insulation board core materials.
First of all, fumed silica is an ultra-fine nanomaterial with a primary particle size of only 7-40nm and a high specific surface area of 400㎡ / g. Therefore, the aggregates and the voids in the particles are very small, and the porosity is also relatively small. High; second, the morphology of fumed silica is a three-dimensional dendritic silica aggregate formed by the sintering of silica primary particles, and then connected by hydrogen bonds and van der Waals forces to form silica agglomerates, so Small bulk density (bulk density is 30-60g / L); In addition, fumed silica itself is prepared at high temperature (1200-2100 ° C), so it has high temperature resistance. Finally, the molding process is relatively simple, and it can be directly mixed with other additives such as infrared shielding agents, adhesives, and reinforcing agents. Compared with core material filling materials such as aerogel, fumed silica has obvious advantages in production cost, production efficiency, electrical performance, thermal stability and service life.
With the continuous popularization of fumed silica in downstream industries, vacuum insulation panels have gradually become the focus of fumed silica.