Preparing polyurethane prepolymer, useful to prepare polyurethane/polyurea elastomer, comprises contacting diphenylmethane diisocyanate with polyol and removing non-reacted diphenylmethane diisocyanate by distillation

摘要

Preparing a polyurethane prepolymer (I), comprises contacting diphenylmethane diisocyanate containing >= 80 wt.% of 2,4'-isomers, with a polyol to a reaction and removing the non-reacted diphenylmethane diisocyanate from the obtained prepolymer by distillation, where the distillation is thin layer distillation and/or shortcut distillation. Independent claims are included for: (1) the polyurethane prepolymer, obtained by the process, where the obtained prepolymer contains = 1 wt.% of free diphenylmethane diisocyanate; (2) preparing a polyurethane/polyurea-elastomer, comprising reacting (I) with an amine chain extender; and (3) the polyurethane/polyurea-elastomer, obtained by the above process.