Vapor-phase silica, commonly known as fumed silica, is an amorphous nanometer white powder with surface hydroxyl, which is produced by the hydrolysis of silicon halides (mainly methyltrichlorosilane and tetrachloride, and a small number of enterprises use trichlorosilane) in the oxyhydrogen flame at high temperature. It is a white flocculent powder under normal conditions. This product has the characteristics of small particle size, large specific surface area, high chemical purity, and good dispersibility. The performance of fumed silica in reinforcement, thickening, thixotropy, anti-sedimentation, sagging resistance, adsorption, heat insulation and other aspects is better than that of precipitation products. Because its molecular structure is similar to that of silicone rubber, it can significantly improve the tensile strength of silicone rubber products, improve the elastic modulus and elongation, so its use in the field of silicone rubber is large. As the preparation process of fumed silica is more complex and the market price is higher, in addition to being mainly used for silicone rubber, it is also widely used as functional additives in ink coatings, synthetic resins, chemical mechanical polishing, composite materials, colloidal batteries, defoamers, sewage treatment, agriculture, cosmetics, food, medicine, thermal insulation materials and other related fields.
At the beginning of the 20th century, with the rapid development of the rubber industry around the world, the reinforcement filler of the rubber industry was mainly zinc oxide. By the 1920s, with the successful trial production of Carbon Black, a new era of rubber reinforcement was created. The mechanical properties of rubber were greatly improved by using carbon black for rubber reinforcement. However, the biggest disadvantage of carbon black was that it was a black powder, Its color attribute determines that carbon black cannot be used to prepare light or colored rubber products. By the 1940s, German Degussa Company had successfully developed the process of preparing fumed silica by hydrolysis of silicon tetrachloride at high temperature in oxyhydrogen flame. With the appearance of fumed silica products, it gave rubber and silicone rubber products excellent tensile strength and tear strength, breaking the situation of black rubber monopolizing the market.
In 2021, the global fumed silica production capacity will be 458900 tons/year. In 2021, the global fumed silica production will be about 324000 tons, an increase of 8.00% year on year. The average annual growth rate of global production in 2017-2021 was 4.60%.
From the perspective of the global consumption structure of fumed silica, the silicone industry is the main consumption area of fumed silica, with silicone rubber as the main. Silicone rubber has good resistance to high and low temperature, heat insulation, insulation, moisture, chemical corrosion, pollution and physiological inertia. It plays an irreplaceable role in aerospace, aviation, national defense industry, machinery manufacturing, building decoration, biomedicine and other fields, and is recognized as a new advanced synthetic material. The most important role of fumed silica in silicone rubber is reinforcement. Adding fumed silica can significantly improve the strength and mechanical properties of silicone rubber products. In addition, it can also improve the high temperature resistance and chemical resistance of silicone rubber, so that silicone rubber can be used in a wider range of fields.
