E.i. Dupont De Nemours and Company

Michael Warren Ott

Robert William Johnson

Brian William Sullivan

Rajeev Lochan Gorowara

Robert Elroy Marganski

This invention relates to a new method for making a photodurable, aqueous titanium dioxide (TiO.sub.2) pigment slurry. The method involves mixing amorphous alumina, TiO.sub.2 pigment particles, water, and at least one dispersant to form the slurry. The initial slurry comprises at least about 78 wt. % TiO.sub.2 solids and at least about 3 wt. % alumina. The resulting slurry may be diluted to a lower TiO.sub.2 solids content and subsequently screened and media-milled. The titanium dioxide pigment slurry is suitable for use in coatings formulations such as paints.

Method for making a photodurable aqueous titanium dioxide pigment slurry

This invention relates to a new method for making a photodurable, aqueous titanium dioxide (TiO.sub.2) pigment slurry. This method involves reacting titanium tetrachloride, aluminum chloride and an oxygen-containing gas in the presence of a nucleant in the vapor phase to produce TiO.sub.2 pigment. A sufficient amount of aluminum chloride is added to provide at least 2 wt. % alumina in the TiO.sub.2 pigment. The TiO.sub.2 pigment is separated from the reaction gases; and mixed with sufficient water to produce a TiO.sub.2 slurry comprising at least 78 wt. % TiO.sub.2 solids. The slurry may be used in coating formulations such as paints.

A process for enhancing the optical efficiency of TiO.sub.2 slurries is disclosed.

TiO.sub.2 slurry process

Disclosed is a process for substantially increasing the content of particles having a size of less than 10 microns in a titanium dioxide slurry, comprising subjecting a starting material slurry containing at least 0.5% by weight of titanium dioxide particles of at least about 10 microns to media milling, whereby the content of particles greater than 10 microns is reduced by a factor of 5.

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Newark, DE, United States of America

Michael Warren Ott