Basf Aktiengesellschaft

Karl Roth

Rudolf Polster

Reinhard Sappok

Alois Wiesenberger

Fritz Guellich

Strong, transparent and readily dispersible copper phthalocyanine pigments are obtained by grinding the crude pigment in the presence of from 1 to 10% by weight (based on the crude pigment) of an organic liquid at from 90.degree. to 140.degree. C., the pigment forms obtained giving printing inks with very good flow characteristics.

Preparation of copper phthalocyanine pigments of the beta-modification

Readily dispersible pigment granules are prepared by dispersing, in an aqueous suspension of the pigment, by thorough stirring, a gas which does not react with the suspension in fine bubbles under essentially atmospheric pressure and converting the resulting pigment suspension into pigment granules by spray drying or by mechanical removal of the liquid, shaping of the still moist pigment cake and subsequent drying.

Preparation of readily dispersible pigment granules

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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Limburgerhof, Germany

Karl Roth