| abstract |
Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m²/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt.%, comprising the following steps: - water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, and - metal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt.% results, and, after all the metal oxide powder or metalloid oxide powder has been added, - the feed device closes and shearing continues in such a way that the shear rate is in the range of between 10000 and 40000 s-1, and - then, by dilution, the predispersion is adjusted to the desired solids content of the dispersion while maintaining the dispersing conditions. |