Modified polyisocyanates with biuret structure and process for their preparation

摘要

Modified polyisocyanates with biuret structure containing terminal urethane groups and having general formula: <IMAGE> (I) in which R1 is an aliphatic, cycloaliphatic or aliphatic-cycloaliphatic radical, simple or substituted, and R2 can have the same meanings as R1 or can be the radical R3(OCnH2n)x-. Process for the preparation of modified polyisocyanates having biuret structure containing terminal urethane groups having general formula (I) consisting in reacting an organic diisocyanate with water or with a compound which splits off water, in the presence of a compatibilizing agent having a hydrogen atom reactive towards the isocyanate group, as it can be determined by Zerewitinoff's method.