The fumed silica is an amorphous silica product prepared by hydrolysis of an organohalosilane at elevated temperatures. The main particle size is between 7 and 40 nm, and the specific surface area is generally greater than 100 m2 / g. The product has a high purity and the silicon content is not less than 99.8%. Gas phase white carbon has been industrialized since the 1940s. In the past few decades, no silica lung disease caused by inhalation of silica has been found. The International Association for Research on Cancer Research (IARC) does not have sufficient evidence to prove that synthetic amorphous silica is carcinogenic to humans or animals, and studies include quartz carcinogens, in addition to the mandatory document (67/548 / EEC), which states that amorphous Silicon is a dangerous cargo.
Due to its good stability, physiological inertia, thickening and so on, it can be widely used in daily life. In human care products, fumed silica is a very important and very effective additive, and a small amount can produce significant effects. Because there are many hydroxyl groups on the surface of the fumed silica, the interaction between the particles is relatively strong. In the liquid system, the high-efficiency gas-phase silica dispersion system interaction and the formation of a three-dimensional network make the viscosity of the system increase while resting. It can effectively prevent the flow of the system, and when properly applied to shear stress, the three-dimensional network is destroyed, and the liquid flow system can be re-formed when the shear stress is removed, and a "gel system" can also be formed.
Therefore, in the thixotropic thickening function, it can be used for gel or paste products such as toothpaste, sunscreen, mask, etc., and the amount thereof is generally 1 to 3%, and some are as high as 4 to 8%. In pearlescent nail polish or spray, fumed silica plays an important role in suspension, so that various components are uniformly dispersed in the system to prevent sedimentation and improve the storage stability of the system. Among hair care products, fumed silica is widely used. For example, anti-dandruff shampoos contain active ingredients such as zinc sulfide, salicylic acid, zinc sulfate, and zinc, most of which require dispersion and suspension of good morphology in the system, and the addition of fumed silica can meet the requirements.
In oily aquatic products, there is usually a greasy feeling, and the addition of fumed silica can reduce the greasy, sticky feeling. Gas phase silica can increase the temperature and stability of the pH in the oil. The addition of fumed silica to the surface of the fumed silica not only improves the texture but also improves the water resistance of the water, generally in the range of 0.5 to 3%. The surface treatment of fumed silica improves the moisture resistance of patches and gels and is very beneficial for lipsticks, eyebrows, oils, cosmetics, whitening creams and sunscreens. It is characterized by particle size and spherical particle shape, which effectively reduces the internal friction of the rubber and improves the dispersion performance. The low chemical activity of the particles prevents structural effects. In this study, the application of special carbon black in natural rubber was studied, and the application of carbon black in natural rubber was discussed.
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