Natural silica through the grinding process to make quartz sand (powder), more impurities, the main ingredient is silica, can not be called white carbon black, nor extinction performance, can only be used as filler in the paint, and no extinction effect, and as a coating used in white carbon black matting agent is mainly synthetic silica, gas phase white carbon black and precipitated silica 2, its microstructure is amorphous or glassy. The silica sand was synthesized by precipitation method, and then the high temperature melting reaction of sodium hydroxide or natrium carbonate in the kiln was processed.
Fumed silica is produced by hydrolysis of Si-si vapor in the hydrogen-oxygen flame, and its reaction is as follows:
Compared with natural silica, silica is high in purity, inert and resistant to ultraviolet light. Amorphous silica refractive index is 1.46, and the coating industry in a lot of resin refractive index similar, so amorphous white carbon black can be used as matting agent in coatings, has good optical properties.