A dispersion in an aromatic polyisocyanate of a reaction product of the polyisocyanate and an amine having the formula: ##STR1## wherein Q represents hydrogen or hydrocarbyl and R represents a hydrocarbyl radical selected from radicals of the formulae: ##STR2## or wherein R and Q together with the attached nitrogen atom form a piperidine, morpholine or pyrolidine ring bearing a hydrocarbyl radical on at least one of the carbon atoms adjacent to the nitrogen atom.