Synthesis Mechanism and Performance Evaluation of the Viscosity Adjustable Hexamethylene Diisocyanate Trimer

This work proposes a new preparation method for polyisocyanate with adjustable viscosity using hexamethylene diisocyanate (HDI) as a raw material. The innovation of this method lies in the continuous recovery or supplementation of HDI during the reaction process, resulting in a mass percentage of HDI in the reaction system of 30–80%. The reaction system is then heated and further reacted. The viscosity range of polyisocyanate products can be adjusted and expanded by controlling the mass percenta