Process for hydrophobizing silicas and silicates with organosilanes

摘要

Finely divided hydrophobic silica or silicate is produced by treating the dry, moving particles with an organic silane at elevated temperature. The silica or silicate which had been prepared by wet precipitation or pyrogenically and which is in powdered form is heated to a temperature of about 200 DEG to 300 DEG C. with agitation and is brought to a fluidized condition and then is treated dropwise with an organosilane which is stable and boils below 300 DEG C.