How to improve the applicability of diazo pigments

摘要

The technical application properties of diazo pigments of formula (I) are improved by (i) adding sulfite ion as hydrogen sulfite or disulfite to weak acidic or neutral aq. suspended soln. obtd. when coupling (I); and (ii) heating for 30min-2hrs at 50-100 deg.C. In the formula, R1 and R2=Me, methoxy, ethoxy and Cl, X=H or Cl, m and n=0 or 1-3 integer independently.