E.i. Dupont De Nemours and Company

Alvin Allen

John Steven Gergely

Narayanan Sankara Subramanian

Russell Bertrum Diemer, Jr

Pratibha Laxman Gai

Glenn R Evers

Russell Bertrum Diemer

The present invention provides a process for producing titanium dioxide (TiO.sub.2) pigment having a coating comprising silica and a second oxide selected from the group consisting of oxides of boron, phosphorus, magnesium, niobium, germanium, and mixtures thereof, comprising the steps of (a) reacting titanium tetrachloride (TiCl.sub.4) in the vapor phase with an aluminum compound and an oxygen-containing gas in a reactor at a temperature in the range of about 900.degree. C. to about 1600.degree. C. to provide a gaseous suspension comprising TiO.sub.2 particles, (b) contacting the gaseous suspension comprising the TiO.sub.2 particles with a silicon halide and an oxide precursor of boron, phosphorus, magnesium, niobium, germanium, and mixtures thereof, and (c) cooling the gaseous suspension to produce TiO.sub.2 pigment having a coating comprising silica and a second oxide.

Process for producing coated TiO.sub.2 pigment using cooxidation to

The present invention provides a process for producing titanium dioxide (TiO.sub.2) pigment comprising boron oxide (B.sub.2 O.sub.3), comprising the steps of: (a) reacting titanium tetrachloride (TiCl.sub.4) in the vapor phase with an aluminum compound and an oxygen-containing gas in a reactor at a temperature in the range of about 900.degree. C. to about 1600.degree. C. to provide a gaseous suspension comprising TiO.sub.2 particles, and (b) contacting the gaseous suspension comprising the TiO.sub.2 particles with a boron compound to produce TiO.sub.2 pigment comprising B.sub.2 O.sub.3.

Process for the addition of boron in a TiO.sub.2 manufacturing process

Titanium dioxide pigment prepared by the high pressure (e.g., 10-200 PSIG) oxidation of TiCl.sub.4 vapor is improved with respect to carbon black undertone, specific surface area, and gloss properties by the addition of a nucleant consisting essentially of a cesium substance which is present in the amount of about 8-2,000 parts per million, based on the weight of the TiO.sub.2. The foregoing process is also used wherein the residence time of the reactants in the mixing zone of the reactor is about 1-16 milliseconds.

TiO.sub.2 manufacturing process

A coated titanium dioxide pigment and the process for its preparation consisting essentially of a core of pigmentary titanium dioxide (TiO.sub.2), a dense inner coating of dense amorphous silica (SiO.sub.2) in an amount from 1 to 10% by weight, based on the uncoated pigment, and, optionally, up to 15% of alumina (Al.sub.2 O.sub.3) and a porous outer coating of porous silica (SiO.sub.2) and alumina (Al.sub.2 O.sub.3), said porous silica being present in an amount from 0.5 to 15% by weight and said alumina being present in an amount from 0 to 15% by weight, based on the uncoated pigment. As a component of coating compositions, this pigment providesa high degree of hiding power and durability for indoor and outdoor applications.

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Claymont, DE, United States of America

Alvin Allen