SILICATE BASED AND POLYSALT CONTAINING HOLLOW MICROSPHERES WHICH HAVE BEEN SURFACE MODIFIED WITH MULTIVALENT METAL

摘要

Non-fused hollow glass microspheres that consist primarily of silicate are rendered more water-resistant by treatment with multivalent metals. The hollow microspheres are slurried with water and then a solution of a multivalent metal salt such as Al2(SO4)3 is added to the slurry. The rate of the addition is controlled so that the pH can be regulated. Separating, washing and drying complete the preparation. The microspheres so prepared are characterized by a weight % ratio of "polysalt" solids to sodium silicate solids of 0.02:1 to 2.0:,1, said sodium silicate containing 1.5 to 4.0 moles of SiO2 per mole of Na2O; a particle size of 35 to 2000 microns; a bulk density of 2 to 20 lbs/cu.ft., less than 7% moisture and 0.1 to 5.0% of a multivalent metal that decreases the solubility of the microsphere in water.