Application of fumed silica in daily necessities
Fumed Silica is a kind of amorphous silica, which is prepared by hydrolysis of organohalosilane at high temperature. The main particle size is between 7-40 nm, and the specific surface area is generally greater than 100m2 / g. The purity of the product is very high, and the silicon content is not less than 99.8%. Fumed silica has been industrialized since 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 (IARC), there is not enough evidence to prove that synthetic amorphous silicon oxide has carcinogenic effect on human or animals, and the research includes quartz carcinogens. In addition to the mandatory document (67 / 548 / EEC), amorphous silicon is a dangerous goods.
Because of its good stability, physiological inertia, thickening and other characteristics, it can be widely used in daily life. In human care products, fumed silica is a very important and effective additive, a small amount of which can produce significant results. Because there are many hydroxyl groups on the surface of fumed silica, the interaction between particles is relatively strong. In the liquid system, it is easy for the dispersion system of fumed silica to interact with each other and the formation of three-dimensional network, which increases the viscosity of the system. At the same time, the rest can effectively prevent the flow of the system. When the three-dimensional network is correctly applied to the shear stress, the system of fluid flow is destroyed. When the shear stress is eliminated, it can Forming a network can also form a "gel system".
Therefore, in thixotropic thickening function, it can be used for toothpaste, sunscreen, mask and other gel or paste products. Its dosage is generally 1 ~ 3%, some of which are as high as 4 ~ 8%. In pearlitic nail polish or sprays, fumed silica plays an important role in suspension, so that all components can be dispersed evenly in the system to prevent settlement and improve the storage stability of the system. In hair care products, fumed silica is widely used. For example, anti dandruff shampoo contains active ingredients such as zinc sulfide, salicylic acid, zinc sulfate and zinc. Most of the ingredients need to be dispersed and suspended in the system in a good form. The addition of fumed silica can meet the requirements.
In oily aquatic products, there is usually a greasy feeling. Adding fumed silica can reduce the greasy and viscous feeling. Fumed silica can improve the temperature and stability of pH value in oil. The sunscreen treated with fumed silica can not only improve the texture of sunscreen, but also improve the water resistance. The general dosage is 0.5 ~ 3%. Fumed silica treatment improves the moisture resistance of patches and gels, and is very beneficial to lipsticks, eyebrows, oils, cosmetics, whitening cream and sunscreen. It is characterized by particle size and spherical particle shape, effectively reducing internal friction of rubber and improving dispersion performance. The low chemical activity of particles can prevent structural effects. In this study, the application of special carbon black in natural rubber was studied, and the application law of carbon black in natural rubber was discussed.