Pq Corporation

Bruce D Spivack

David I Netting

James P Cunnion, Jr

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 Al.sub.2 (SO.sub.4).sub.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.

Process for surface modified hollow microspheres

Hollow fibers are prepared by spray drying a solution of a film-former in a volatile solvent. The viscosity of the solution must be 1.5 to 10 times the viscosity that usually results in spheres or microspheres. The preferred film-forming substance is a combination of sodium silicate and a 'polysalt.'

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Norristown, PA, United States of America

Bruce D Spivack