Degussa Aktiengesellschaft

Astrid Muller

Klaus-Dieter Hellwig

J&uuml;rgen Schubert

Aluminum-doped precipitated silicas having a BET surface area of more than 300 m /g and aluminum distributed uniformly in the silica particles are prepared by sequentially heating a mixture of water and sodium silicate at a temperature of from 70 to 86&deg; C. and adding sulfuric acid until half of the sodium silicate is neutralized, then aging the mixture for a time of from 30 to 120 minutes, adjusting the pH of the mixture with sulfuric acid to a range of from 3.0 to 7.0, thereby precipitating the aluminum-doped silica, filtering the aluminum-doped silica from the mixture to form a filtercake and washing the filtercake, followed by drying and/or grinding the washed filtercake. An aluminum salt solution is metered into the mixture at step a) and/or step c). The aluminum-doped precipitated silicas of the present invention may be used in coatings for paper and other media intended for ink jet printing.

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Mömbris, Germany

Astrid Muller