Bayer Aktiengesellschaft

Willy Schiwy

Reinhold Hornle

Hans-Heinz Molls

Reinhard Nebeling

Karlheinz Wolf

Horst Brandt

Jochen Koll

Fritz Bremer

Jurgen Schulze

Ferdinand Hummes

Erhard Schuffenhauer

Peter Schulze

Harry Orttmann

Highly concentrated liquid preparations of disperse dyestuffs are obtained with a low consumption of energy by first adding a dispersing agent to the water-moist dyestuff press-cake to convert it into a form in which it is capable of flow, subjecting this product to wet grinding and increasing the dyestuff content of the resulting, insufficiently concentrated dispersion in a second step by means of a membrane separation process, for example pressure permeation.

Process for producing liquid dyestuff preparations

Chemical reaction products, obtained in an alkaline medium and which require the addition of a dispersing agent, are neutralized by addition of a free surface-active acid to which, after its preparation, basic agents have not been added or have only been added up to a pH value of 3.

Process for the neutralization of basic reaction compositions

Process for the production of granular mixtures of vat dyestuffs and/or disperse dyestuffs, characterized in that liquid or pasty, finished formulations of two or more vat dyestuffs and/or disperse dyestuffs are spray-dried together to form granules.

Granular preparation of vat dyestuffs and/or disperse dyestuffs

Dyestuff dispersions and dyestuff solutions free from salt or at least having a low salt content are obtained in that the diazotization is carried out with addition of free dispersing agent acid to which, after the synthesis, either no basic agents are added or basic agents are added only up to a pH value of 3. The disclosed process gives dyestuff compositions of low salt content and results in readily dispersible dyestuffs when water insoluble dyestuffs are prepared and stable solutions when water soluble dyestuffs are prepared. The process is widely applicable and chemical constitution of the dyestuffs is conventional.

Process for preparation of azo dyestuffs by coupling in presence of

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Leverkusen, Germany

Willy Schiwy