Bayer Corporation

Tanya T Harper

James J Good

John G Skabardonis

Samuel S Murphree

This invention relates to a process for the preparation of storage-stable dye dispersions of alkali metal salts of anionic azo direct dyes by (a) preparing an aqueous slurry of an alkali metal salt of an azo direct dye, said salt having a solubility in water at 25.degree. C. of about 0.1 to about 15% by weight, by azo coupling one or more aromatic diazonium salts with one or more couplers while maintaining a pH of at least about 5 by adding a basic alkali metal compound in the absence of a nitrogen-containing base; (b) optionally, stirring the aqueous slurry at a temperature of about 5.degree. C. to about 100.degree. C. for up to about six hours; (c) optionally, adjusting the temperature of the aqueous slurry to about 5.degree. C. to about 40.degree. C.; and (d) adding to the aqueous slum/a viscosity enhancing agent in an amount sufficient to obtain a viscosity, determined at a temperature of about 20.degree. to about 25.degree. C., of about 500 to about 5000 centipoise (preferably 800 to 1500 centipoise) and 0 to about 10% by weight, based on the total weight of the dye dispersion, of a humectant.

Growing community of inventors

Goose Creek, SC, United States of America

Tanya T Harper