There are two broad categories of Fumed Silica: non-treated and treated, the former being hydrophilic and the latter being hydrophobic. The non-treated fumed silica refers to a silica micropowder formed by a gas phase method, which is directly accumulated, purified, collected, compressed, and packaged, and has no hydroxyl group remaining on the surface of the silica particles without being treated by other chemical agents. Hydrophilic. The so-called treated fumed silica means that the non-treated fumed silica is subjected to chemical treatment, and the surface hydroxyl group is substituted by a corresponding group (generally a hydrophobic group), thereby being hydrophobic. This type of product is divided into two sub-categories: fully processed and incompletely processed.
Hydrophobic silica cannot be wetted by water and cannot be dispersed in water. Although the density of hydrophobic silica is greater than the density of water, they can float above the water.
In order to solve some special technical problems in the industry, various types of Hydrophobic Fumed Silica have been developed. For example, by treating a hydrophilic grade of fumed silica with silane or siloxane to produce hydrophobic fumed silica, in the final product, the chemical treatment agent is chemically bonded to the original hydrophilic oxidation. On the object. In addition to the above advantages of hydrophilic products, hydrophobic fumed silica products are characterized by low hygroscopicity, good dispersibility, and rheology-adjusting ability even for polar systems. Some products, after structural modification on the basis of hydrophobic treatment, can develop new products and improve product performance for customers. For example, in liquid systems, hydrophobic fumed silica can achieve high levels of addition with little effect on the viscosity of the system.
The function of hydrophobic fumed silica:
1. The most suitable rheology in processing
2. Thickening of polar liquid into epoxy resin
3. Reinforcement of silicone elasticity
4. High addition amount, into molded products
5. Good hydrophobicity and improved corrosion resistance
6. Improve dielectric properties, such as in cable composites
7. Powder glidants, such as in fire extinguishing agents
8. Improve scratch resistance in paints and plastics
Hydrophilic Fumed Silica is produced by hydrolysis of a volatile chlorosilane in an oxyhydrogen flame. From a chemical point of view, these loose white powders are composed of high purity amorphous silica. Can be dispersed in water.
In addition to its use in polyester, silicone, paints and coatings in the traditional industrial sector, hydrophilic fumed silica products are increasingly used in high-tech applications. The nanoparticle properties and high anger of fumed silica have led to their use in the electronics and fiber optic industries.
The hydrophilic fumed silica product has an amorphous structure by X-ray analysis. Depending on the market and the application, we can supply primary particles of different particle sizes and products with a constant surface area. Some fumed silicas can be supplied after compression, and some products are pharmaceutical grade.
The function of hydrophilic fumed silica:
1. Suitable for processing and adjusting to the best rheology
2. Reinforcement of silicone elasticity
3. Thickening of non-polar liquids
4. Glidants for food and industrial powders
5. High chemical purity
6. Excellent insulation properties even at high temperatures
7. Liquid is converted into powder, into medicine, cosmetics
8. Special application in special paper in the paper industry
