Chromium complex azo dyes

Good non-colored negative charging CCAs have been obtained by making non-colored analogues of the 2 1 chromium complex azo dyes. This is achieved by making the metal complex of an aromatic ortho-hydroxy carboxylic acid. Typical examples are the chromium, aluminum, and zinc complexes of di-tert-butyl salicylic acid, e.g., BONTRON E-8136 41 (53) and BON-acid36,41,42 e.g., BONTRON E-82 (54). 

Chromium Complexes Containing Sulfonic Acid Groups. The production of premetallized complex dyes began in 1912, when R. Bohn of BASF synthesized 1 1 chromium complexes and BA SF and CIBA introduced ranges of sulfonic acid containing 1 1 chromium complex azo dyes. No metal other than chromium is suitable for this class of dyes. 

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