Ciba Specialty Chemicals Corporation

Klaus Ruf

Yves Grandidier

Albert Riegler

Urs Schlatter

Takashi Deno

Hanspeter Hauser

Substantially crystalline organic pigments characterized by small particle size and narrow particle size distribution.

Pigments having improved coloristic properties and process for their preparation

This invention relates to 1,4-diketopyrrolo[3,4c]-pyrrole pigments of the formulacharacterized by desirable color properties and novel visible absorbance spectra with a steep slope on the bathochromic side of the absorption maximum in the range of from 500 to 650 nm.

The invention relates to a process for preparing pigments, which comprises These pigments and their use in polymers, printing inks and colours filters are also claimed. The invention in particular relates to a novel pigment form of Pigment Violet 23obtained by above-mentioned process and having higher colour strength and colour saturation as well as excellent other applications properties in particular in printing inks. The invention also relates to a highly crystalline novel form of Pigment Red 254obtained by above-mentioned process, too, and having a steep slope on the bathochromic side of the absorption spectrum's maximum, and the use thereof in particular in colour filters.

The invention relates to crimson-colored pigment mixtures comprising 1,4-diketo-2,5-dihydro-3,6-diarylpyrrolo&lsqb;3,4c&rsqb;pyrrole and quinacridone pigments in separate crystalline phases, having a high tinctorial strength combined with other excellent application properties. The pigments according to the invention can be used in printing inks, especially in printing inks for polychromatic printed products. A substantial constituent of the pigment mixtures according to the invention is 1,4-diketo-2,5-dihydro-3,6-di(4&prime;-chlorophenyl)pyrrolo&lsqb;3,4c&rsqb;pyrrole or 2,9-dichloroquinacridone, which are subjected to kneading with a crystalline inorganic salt and a neutral organic liquid. The invention also relates to a process for the preparation of such pigment compositions, the use thereof in the production of printing inks, and such printing inks themselves.

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Bollschweil, Germany

Klaus Ruf