To provide a method for efficiently removing an organic solvent from a suspension, while preventing formation of lumps, by steam distillation after an aqueous alkali solution is added to the suspension.
This method removes (B) an organic solvent sparingly soluble or insoluble in an aqueous alkaline solution from (C) a reaction mixture of crude phthalocyanine-based compound containing water and the component B, or from (D) a suspension of a phthalocyanine-based pigment containing water and the component B by steam distillation after (E) an aqueous alkaline solution is added to the mixture or suspension. It is preferable that the component E is composed of water and an inorganic salt (e.g. caustic soda) which shows alkalinity when dissolved in water, and the inorganic salt is used at 3 to 20 pts.wt. per 100 pts.wt. of the component C or D. It is also preferable that the steam distillation is effected at the normal pressure or under a vacuum while the vessel is heated from an external source.
ONO KOJI
TAKEI TOSHIO
