Production of small particle size aqueous colloidal silica sols
Abstract
Abstract THE INVENTION IS DIRECTED TO AQUEOUS COLLOIDAL SILICA SOLS WHICH ARE CONCENTRATED, YET ARE IN THE FORM OF EXATREMELY FINELY DIVIDED, DISCRETE, DENSE PARTICLES WHOSE AVERAGE PARTICLE SIZE IN LESS THAN 5 MILLIMICRONS. THPICAL SOLS PRODUCED IN ACCORDANCE WAITH THE INVENTION HAVE THE FOLLOWING CHARACTERISTICS: AVERAGE PARTICLE SIZE DIAMETER 2 BUT LESS THAN 5MU. PERCENT SILICA, AS SIO2 10 TO 25%. PH 9 TO 11. SIO2/NA2O >15. THE INVENTION ALSO IS DIRECTED TO A METHOD OF PRODUCING SUCH SOLS WHEREIN AN ACIDIC AQUOUS COLLOIDAL SILICA SOL HAVING AN SIO2 CONCENTRATION OF 5-10% BY WIIGHT AND A PARTICLE SIZE DIAMETER OF LESS THAN 5 MILLIMICRONS IS ALKALIZED, A PORTION OF THE RESULTING ALKALINE SOL IS HEATED UNDER EVAPORATION CONDITIONS TO A TEMPERATURE NOT GREATER THAN 150* F., EVAPORATION IS MAINTAINED AT CONSTANT VOLUME BY ADDING UNHEATED ALKALINE SOL, AND SAID EVAPORATION IS CONTINUED UNTIL THE SILICA CONCENTRATION IS WITHIN THE RANGE OF 10-25% BY WEIGHT.
Inventors
- 👤 P Vossos
Bibliographic Details
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