Ciba-geigy Corporation

Gunther Zwahlen

Andreas Laely

Lothar Buxbaum

Hans Mollet

Fridolin Babler

Christoph Frey

Remy Jeanneret

Gerhard Umsonst

Georgios Zographos

The invention provides a method for the production of a pigment preparation for coloring linear polyesters in the melt, which comprises forming a concentrate from 20 to 80 parts of pigment and 80 to 20 parts of a polyester which melts between 60.degree. and 160.degree. C., by kneading in the presence of a salt and a solvent or by a flush process, mixing said concentrate with a fibre forming linear polyester, melting the mixture and processing it to granules. The invention also provides the pigment preparation obtained by the process and the linear polyesters colored therewith.

Method for the production of a pigment preparation for coloring linear

An electrophotographic imaging process, wherein the electrically photosensitive particles for the image reproduction consist of a black pigment selected from the series of the anthraquinoid pigments which contain at least 2 anthraquinone radicals or at least 6 condensed rings, of the perylenetetracarboxylic diimides or of the metal complexes of the formula ##STR1## wherein A represents a nitrogen atom or the ##STR2## X represents a hydrogen or halogen atom or an alkyl group of 1 to 6 carbon atoms,

Electrophotographic imaging process using anthraquinoid black pigments

A process for the mass coloration or whitening of linear polyesters, wherein the polyester to be colored is mixed, in the solid or fused state, with a preparation consisting substantially of a colorant or fluorescent brightener which is soluble or insoluble in the polyester, and of a polystyrene with a softening point above 100.degree. C, and the resultant mixture, provided it is not already in the form of a melt, is converted into the molten state and formed into shaped articles. Evenly and deeply colored polyesters are obtained.

Process for the mass coloration or whitening of linear polyesters

A process for the manufacture of an easily isolatable, dustless, readily dispersible pigment granulate which comprises subjecting a suspension of a finely dispersed organic pigment or pigment preparation, in the presence of water-insoluble granulating assistants belonging to the class of natural, synthetic or semi-synthetic resins, esters of dicarboxylic acids, of arylcarboxylic acids, of arylsulphonic acids, of phosphoric and phosphorous acid, phenylsulphonamides or the alkaline salts of fatty acids containing 12 to 14 carbon atoms, but in the absence of wetting agents, in a two-phase system consisting of an aqueous phase and a second liquid phase which consists substantially of an organic solvent that is virtually insoluble in water and in which the granulating assistant is at least partially soluble, to a turbulent mixing until a granulate has formed, then isolating said granulate, which consists substantially of pigment or pigment preparation, granulating assistant and organic solvent, and removing the solvent therefrom.

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Dornach, Switzerland

Gunther Zwahlen