Cabot Corporation

John F Welch

Yuan Yu

Thomas A Kinney

Friedrich K Von Gottberg

Colored pigments having one or more desired parameters and/or properties are described. These parameters and/or properties include: a) a particles size of from about 10 nm to about 300 nm; b) an accusizer number of less than 10 particles/ml of dispersion at 15% solids which are greater than 0.5 micron; c) a filterability such that when in a liquid medium, 100 ml having 10% solids of the colored pigment filters through a 3 micron nylon absolute filter; d) a colored pigment purity of greater than about 80%, based on extractable material; and/or e) a stability such that the above-described properties do not change by more than 50% at 25 degrees C for at least one week. Colored pigments having at least one organic group and having one or more of the above-described characteristics is also described as well as a process for preparing surface-modified colored pigments. The process involves combining at least one treating agent and at least one type of colored pigment(s) in a container to form a mixture and subjecting the mixture to high shearing and introducing at least one diazotizing agent to the mixture at least for a portion of time while the high shearing is taking place, and preferably during the entire time that high shearing is taking place, such that a reaction product is formed and contains surface-modified colored pigment(s).

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Winchester, MA, United States of America

John F Welch