Peter Dilling - Isle of Palms SC
Susan L. Schlegel - Goose Creek SC
Westvaco Corporation - New York NY
An improved lignosulfonate salt composition particularly suited for use as a dyestuff dispersant in azo dyestuff-containing dye systems wherein a sulfonated lignin salt is modified by ion-exchange reaction with an amine compound having a lower dissociation constant and pKa than the dissociation constant and pKa of the cation of the sulfonated lignin salt to provide a dispersant for an azo dyestuff which causes less color reduction of the azo dyestuff than the unmodified sulfonated lignin salt dispersant. More specifically, a sulfonated lignin salt having a relatively high pKa, such as a sodium or ammonium salt, is reacted with a lower pKa amine compound, such as triethanolamine, diethanolamine, or monoethanolamine, in amounts from about 0. 1 to 2. 5 moles per 1,000 grams of lignin to produce an ion exchange reaction between the sodium and ammonium cations and the amine cations to stabilize the lignin dispersant and inhibit its tendency for azo dye reduction in azo dye-containing dye systems.