Production of low-monomer, isocyanate prepolymer for use, e.g. in adhesives, sealants or foam, involves reaction of unsymmetrical di-isocyanate with polyol and catalyst followed by further reaction with another polyol

摘要

A 2-stage method for the production of isocyanate-terminated polyurethane prepolymers involves: (1) reacting (a) unsymmetrical di-isocyanate(s) with (b) polyol(s) with an average mol. wt. (Mn) of 60-3000 in presence of a catalyst at an (NCO):(OH) group ratio of (1.2:1)-(4:1); and (2) adding other polyol(s) to give a total (NCO):(OH) ratio of (1.1:1)-(2:1).