Spheroidal aggregate of platy synthetic hydrotalcite
Reference Number: N 03-06
Inventors: Cox, Sherman D.; Wise, Kenneth J.
Owner: NISTAC
USPTO Link:5364828
Invention Summary
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.