Automatic control of azo coupling processes in the manufacture of azo pigments
AssigneeCiba-Geigy Corporation
InventorsAlexander Hamilton, Colin Nelson
Life of this patent
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Abstract
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.
Claims9
In a continuous process for the manufacture of water-insoluble azo pigments by reacting a diazonium salt and a coupling component where the amount of the diazonium salt in a reaction mixture is monitored by a continual polarographic determination and is automatically adjusted so that there is always a very slight excess of the diazonium salt in the reaction mixture wherein the improvement comprises reacting the diazonium salt and the coupling component where the amount of the coupling component in the reaction mixture is monitored by a continuous dialytic and colorimetric determination and the amounts of both the coupling component and diazonium salt are automatically adjusted so that there is always a slight excess of the coupling component in the reaction mixture.
Dependencies are inferred from the claim text.