To simply prepare the subject polymorph, having a desired particle size and a desired particle size distribution and useful as a pigment for coloring coating materials, etc., by reductively cyclizing phthalonitrile in the presence of an aliphatic alcohol, a redox catalyst, an inorganic base and a specific phthalocyanine derivative.
Phthalonitrile is reductively cyclized in the presence of an aliphatic alcohol, a redox catalyst, an inorganic base and a phthalocyanine derivative (phthalocyanine-sulfonic acid, phthalocyanine-carboxylic acid, an aminomethylated phthalocyanine, a halogenated phthalocyanine, etc.). Thereby, the subject phthalocyanine directly usable as a pigment for coloring printing inks, coating materials and plastics is obtained without passing the phthalonitrile through finishing steps (grinding and/or solvent treatment).
SCHERHAG FRANK (DE)
KLOPP INGO (DE)
HARTMANN ANETTE (DE)
