Treatment of phthalocyanine pigments

Claim 1

IN THE MANUFACTURE OF IMPROVED MICROCRYSTALLINE PHTHALOCYANINE PIGMENTS HAVING HIGH RESISTANCE TO FLOCCULATION FROM AMORPHOUS PHTHALOCYANINE PIGMENTS, THE IMPROVED PROCESS WHICH COMPRISES ADMIXING AN AQUEOUS DISPERSION OF FINELY DIVIDED AMORPHOUS PHTHALOCYANINE PIGMENT WITH A WATER IMMISCIBLE ORGANIC LIQUID SELECTED FROM THE GROUP CONSISTING OF HYDROCARBONS AND HALOGENATED HYDROCARBONS HAVING BOILING POINTS BETWEEN 50* C. AND 250* C., AGITATING THE MIXTURE UNTIL THE PIGMENT IS TRANSFERRED FROM THE AQUEOUS TO THE NON-AQUEOUS PHASE OF SAID MIXTURE, CONTINUING THE AGITATION UNTIL THE AMORPHOUS PIGMENT IS CONVERTED INTO NEEDLE-LIKE MICROCRYSTALS OF LESS THAN 0.5 MICRON AVERAGE LENGTH, REMOVING THE ORGANIC LIQUID FROM SAID MIXTURE TO OBTAIN AN AQUEOUS DISPERSION OF SAID MICROCRYSTALLINE PHTHALOCYANINE PIGMENT, AND SEPARATING THE MICROCRYSTALLINE PHTHALOCYANINE PIGMENT FROM SAID AQUEOUS DISPERSION, THE FINELY DIVIDED, MICROCRYSTALLINE PHTHALOCYANINE PIGMENT SO OBTAINED HAVING HIGH RESISTANCE TO FLOCCULATION.