Cristal Inorganic Chemicals Switzerland Ltd

Ineos Pigments USA Inc.

Lee Chris Mundle

Modasser El-Shoubary

The invention provides a method for enhancing the durability of a titanium dioxide material, the method including mixing citric acid and an alumina source with an aqueous slurry of titanium dioxide particles and water to form a mixture, the mixture having an acidic pH; and raising the pH of the mixture to a pH of no more than about 7.5 to form alumina-coated titanium dioxide particles. The invention also provides a pigmented plastic article including alumina-coated titanium dioxide particles prepared according to the invention dispersed in a polymer material.

Pigment with enhanced durability and plastic materials made therewith

A cost-effective process for loading particulate pigment into a polymer concentrate includes adding a basic pH aqueous solution having a water soluble organic salt to a milled particulate pigment to form an organic-coated particulate pigment. The pH of the basic aqueous solution is sufficiently basic that the water soluble organic salt remains in a salt form. Without a prior micronization step, the organic-coated particulate pigment is mixed with a polymer resin to form a polymer concentrate having from about 50% to about 87% by weight particulate pigment with dispersibility comparable to micronized organic-coated particulate pigment.

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White Hall, MD, United States of America

Lee Chris Mundle