Process for dyeing polyurethane plastics

摘要

A process for dyeing polyurethane plastics is disclosed in which an azo dyestuff derived from an indole or 5-aminopyrazole coupling component and containing at least one group having an active hydrogen atom, e.g. hydroxyl aor amino, is introduced during the reaction forming the polyurethane whereby the dyestuff is bonded to the polyurethane by a covalent bond resulting from reaction of the active hydrogen on the dyestuff with a polyurethane reaction component, e.g. polyisocyanate. The dyed polyurethanes produced by this process having a very high level of fastness, e.g. fastness to bleeding upon overcoating.