Automatic control of azo coupling processes in the manufacture of azo pigments

摘要

Azo pigment coupling process in which the amount of excess diazo or coupling component is continuously monitored and addition of diazo component or coupling component to the reaction is automatically controlled by means of an automatic chemical analyzer which incorporates a dialyser module. The process involves a method of automatically controlling the coupling reaction by a continuous-flow chemical analyzer which continuously samples the reaction mixture and analyzes it for unreacted diazo or coupling component by dialysis and colorimetry, and automatically adjusts the rate of addition of this component to the reaction mixture to keep the concentration of unreacted component within a pre-set range during the period of the reaction.