Basf Aktiengesellschaft

Fritz Guellich

Reinhard Sappok

Alois Wiesenberger

Karl Roth

A process for the preparation of pigmentary forms of phthalocyanine and of insoluble polycyclic compounds, wherein the crude pigment is milled in the presence of one or more acids which have a pK of &lt;4.9 and are non-oxidizing under the milling conditions, until the primary particle size is .ltoreq.0.1 .mu.m, the milled material is then finished in the conventional manner in a solvent in the presence or absence of water, and the pigment is isolated. The pigments give very deep colorations and are very easily dispersible in the media in which they are used.

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Dannstadt-Schauernheim, Germany

Fritz Guellich