LOW COLOR POLYURETHANE PREPOLYMERS FROM PARA-PHENYLENE DIISOCYANATE HAVING LOW FREE ISOCYANATE MONOMER CONTENT AND POLYURETHANES PREPARED THEREFROM

摘要

Co-distilling a mixture of para-phenylene diisocyanate (PPDI) and solvent, collecting the mixture of solvent and PPDI as a solution, reacting this solution with a polyol to form a prepolymer, and then removing unreacted PPDI by distillation in the presence of one or more solvents provides lower color prepolymer and higher quality polyurethane resin than a similar process that omits the co-distillation of PPDI and solvent prior to reaction with the polyol.