Pigments having improved

December 7, 2005

Pigments having improved
coloristic properties
Patent No. U.S. 6,911,075 B2
Ciba Specialty Chemicals Corp. has obtained a patent for a process for preparing a pigment, which comprises a subjecting a crude pigment or mixture of crude pigments and a crystalline inorganic salt or mixture of crystalline inorganic salts together, essentially in the absence of other constituents, to the action of a rotor having a tangential speed of at least 10 m/s, so that a temperature of at least 80°C is attained by means of friction effects; and subsequently kneading the product with an organic liquid, optionally adding substances selected from the group consisting of inorganic salts, inert additives and colorants wherein the pigment is an organic pigment of the quinacridone, anthraquinone, perylene, indigo, quinophthalone, indanthrone, isoindolinone, isoindoline, dioxazine, azo, phthalocyanine or diketopyrrolopyrrole series or inorganic pigment; the crystalline inorganic salt is a salt soluble in water to the extent of at least 10 g/100 ml; the organic liquid is soluble in water to the extent of at least 10 g/100 ml, and the crystalline inorganic salt being further insoluble or soluble to an extent of <100 mg/l in the organic liquid at 20° C.

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