Tioxide Group Services Limited

Guy Decelles

John Robb

A novel inorganic particulate powder coated with an organic polymer is claimed. The product is obtainable by dispersing in water inorganic particles at a pH higher than their isoelectric point in the presence of a polymeric polybasic acid as a dispersing agent to produce particles having a modified isoelectric point. The pH of the dispersion is then adjusted to a value below 9 but above the modified isoelectric point and an ethylenically unsaturated monomer is polymerized in the presence of the dispersion so as to coat the inorganic particles with polymerized monomer. A method for forming the particles is also claimed. The particles prepared by the method have been shown to be uniformly and discretely coated with an organic polymeric coating and can be used in many applications where it is desired to disperse inorganic particles in organic media such as paints, inks and plastics compositions.

Coated inorganic particles

Titanium dioxide carries an ester or a partial ester of an hydroxy compound containing 1 to 6 OH groups and an aliphatic saturated C.sub.10 to C.sub.22 monocarboxylic acid. The product is easily dispersible in plastics compositions, particularly masterbatches. The titanium dioxide can also be coated with one or more hydrous oxides. The product is prepared by milling the titanium dioxide in a fluid energy mill in the presence of the ester or partial ester.

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Yarm, United Kingdom

Guy Decelles