E.i. Dupont De Nemours and Company

Sandra L Witman

An-Gong Yeh

James Lewis Hohman, Jr

Harry J Spinelli

Robert P Held

Dhiren V Patel

Michael J Eiseman

Yia-Ching Ray

Robert Paul Held

James L Hohman

Harry Joseph Spinelli

A process is provided in which a pigment is oxidated with ozone in an aqueous environment in which the mixture of ozone, water and pigment is subjected to a dispersive mixing operation; and/or the pH of the mixture is maintained in a range of 6-8, whereby the pigment is self-dispersing and preferably has an acid value of less than 3 &#x3bc;moles/M. Pigments from this process and ink jet inks containing the self-dispersing pigments, are also provided.

Self-dispersing pigment and process of making and use of same

A method of producing self dispersible organic pigment particles stabilized by the method. The method includes modifying organic pigment particles and then contacting the surface modified particles with an aqueous vapor entrained in a carrier gas to produce the stabilized organic pigment particles. Typically the pigment particles are modified by exposing their surfaces to ozone or a plasma-activated process gas. The surface stabilizing method prevents the violent exothermic reaction, which occurs when surface modified pigment particles are exposed to ambient air. The method is accomplished in a device, which includes a reactor, means for introducing in the reactor aqueous vapor entrained in a carrier gas and an agitator assembly for deagglomerating during surface modification the pigment particles placed in the reactor. The stabilized particles of the present invention are also well suited for use in ink jet inks, pigmented waterborne and solvent borne coating compositions, and pigmented powder coating compositions.

Method of producing stabilized organic pigment particles and device therefor

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Wilmington, DE, United States of America

Sandra L Witman