Method for making low sodium hollow glass microspheres

Abstract

Low sodium hollow glass microspheres containing less than about 3 wt. % Na.sub.2 O are produced from aqueous precursors. The method comprises a) forming an aqueous glass precursor solution or slurry by combining sources of cations contained in the glass, the solution or slurry comprising all of the glass cations in proportions substantially identical to those in the glass, b) forming the solution or slurry into droplets, and c) heating the droplets to form the microspheres. The precursor may also contain surfactants, blowing agents or other known expedients. Nonionic fluorocarbon surfactants are preferred. The droplets may be formed by spraying or any other known technique. The droplets may be spray dried prior to heating step c).

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