Process for the production of dis-azo pigment whose amine content is small, and pigment produced by said process

Abstract

A process for the production of a dis-azo pigment which is excellent in sanitary condition and almost free of a residual coupler component and decomposition products derived from the residual coupler component, and has a reduced aromatic amine content, and a dis-azo pigment produced by the said process, the process comprising the steps of (a) coupling-reacting a solution of a tetrazonium salt of benzidine with a slurry of acetoacetanilide of which the amount is stoichiometrically excess relative to an amount of said tetrazonium salt, to prepare a dis-azo pigment slurry, and (b) adding a halogen to the dis-azo pigment slurry to treat the acetoacetanilide in said slurry.

Dependencies are inferred from the claim text.