Verfahren zur Inkorporierung von Wasser in feinst verteilter Kieselsaeure

摘要

A surface envelope of silica over water droplets is formed by intensively shaking water and hydrophobic silica or by atomizing water and hydrophobic silica in a cyclone into which they are introduced through separate nozzles. The hydrophobic silica is made by contacting silica (of particle size 10-40 mm and of B.E.T. surface about 150 m2/g and carbon content 1-1.5% by weight) with 0.75 m. mol. per gm. of silica of a haloalkyl silane, e.g. dimethyldichlorosilane as disclosed in Specification 1,031,764. The water droplets can have a size of 2-3 x 10-2 mm. The product is a white powder having a water to silica content of 5 to 10:1 parts by weight. On freezing and thawing the product or under pressure the water separates from the silica. The water in the product may be present in an aqueous solution, e.g. of pharmaceutical or cosmetic substances. The product can be used as a fire-retardant.