Kain Chemical: What is the modification principle of silica?

Surface modification of white carbon black is to use certain chemical substances to make the surface hydrocarbon groups of white carbon black react with chemical substances through certain processes. Reaction to eliminate or reduce the amount of surface active silanol groups to achieve the purpose of changing surface properties.

Surface modification of white carbon black is divided into inorganic modification and organic modification. Inorganic modification, such as wrapping SiO2 with Tio2.

Organic modification is the main method of silica modification. The key technology of this modification method lies in organic Groups replace the surface hydrocarbon groups of silica, a step called organosilylation.

Commonly used methods for organic modification are divided into dry method, wet method and autoclave method. The dry method is applied to the contact reaction between dry silica, modifier (organic matter) and steam in a solid reactor or fluidized bed reactor under high temperature conditions.

Abroad, the research on surface modification of silica started in the 1960s and 1970s. The focus includes modification methods, modification processes, selection of modifiers, etc. A large number of them have been produced in Germany, Japan and the United States.

There are two main types of wet modification:

First, a solution composed of dry silica, modifier and an organic solvent (benzene, toluene, etc.) is heated and boiled, refluxed for reaction, and then separated and dried. The main features of this method are simple process, easy control of product quality, and low modifier consumption. The disadvantage is that its product post-processing process is complicated and causes organic solvent pollution, making it difficult to achieve large-scale industrial production.

Second, prepare the dried silica or washed Precipitated silica filter cake into an aqueous solution slurry, and add water-soluble organic solvents such as alcohols or surfactants, etc. Then, a modifier is added to carry out the organosilane reaction; and then the modifier is added to the suspension after the precipitation reaction is completed. The main features of this method are simple process, less auxiliary equipment, and the ability to modify precipitated silica, especially semi-finished products of precipitated silica, which is beneficial to reducing costs.