Spheroidal aggregate of platy synthetic hydrotalcite
Reference Number: N 03-06
Inventors: Cox, Sherman D.; Wise, Kenneth J.
According to the present invention, a broad size range of substantially spheroidal hydrotalcite aggregates can be synthesized, having average spherical diameters of up to about 60 .mu.m. Individual hydrotalcite particles within the aggregates are substantially platy in nature, while the aggregates themselves are substantially uniformly spheroidal in shape.
The hydrotalcite compositions are prepared from aqueous solutions of soluble magnesium and aluminum salts, which are mixed in a molar ratio of from about 2.5:1 to 4:1, together with a basic solution containing at least a two-fold excess of carbonate and a sufficient amount of a base to maintain a pH of the reaction mixture in the range of from about 8.5 to about 9.5.
The product particle size is determined by controlling process parameters including reaction temperature, reaction stirring speed, reaction pH, reactant addition rates and reactant concentrations.
The combination of properties exhibited by the spheroidal aggregates of this invention enable them to be used in a wide variety of applications. Such uses include, but are not limited to: specialty fillers in plastics, paints, ceramics and paper; catalysts and catalyst carriers; chromatography media; adsorbents; and carriers for fragrances, flavors and pesticides.