Pigments and process for their preparation

摘要

Pigment composition (I), comprising (a) a dye fixed in (b) a solid resin consisting of the reaction product of (b1) an oligomerised polyisocyanate and (b2) a mixture of polyfunctional compounds with active hydrogen. Also claimed is (i) a process for the production of (I), by mixing (a) with (b1) and (b2), reacting at elevated temperature to form a solid resin, and milling the resin to the required particle size; (ii) a data storage medium containing composition (I), especially a security document or a consumer product, on which composition (I) is printed in the form of a code.