Abstract: The present invention concerns aqueous coating systems, providing an aqueous coating composition which comprises water, a film-forming component and at least one inorganic pigment surface treated with one or more organosilicon compounds from the alkyltrialkoxysilanes, the dialkyldialkoxysilanes and mixtures, oligomers, and copolymers of the alkyltrialkoxysilanes and dialkyldialkoxysilanes, wherein the alkyl groups contain from three to six carbon atoms and optionally contain an oxygen atom or contain fluorine and/or chlorine heteroatoms. By controlling and limiting the amounts used of these organosilicon surface treatments, the dispersibility of a conventionally hydrophilic inorganic pigment such as titanium dioxide is not materially adversely affected, but improvements are at the same time afforded in terms of the compatibility of the pigment with the film-forming component, as demonstrated by improved tint strength and gloss properties in a paint composition.

Abstract: An improved process is described for manufacturing zirconia-treated titanium dioxide pigments, wherein the zirconia treatment is accomplished in the process of fluidizing a titanium dioxide filter or press cake and then drying the same, through the addition to the filter or press cake of one or more alkaline water-soluble zirconium reagents selected from ammonium zirconyl carbonate, the water-soluble ammonium zirconyl carboxylates and mixtures of these. Aqueous solutions of such zirconium reagents, in addition to being effective for imparting a zirconia surface treatment to the titanium dioxide materials, also prove to be effective fluidizing agents for forming high solids dispersions of the zirconia-treated titanium dioxide pigment materials which can be spray dried without substantial dilution and excessive energy requirements.