Linear HDI urethane prepolymers for rim application

摘要

The present invention is directed to polyurethane moldings produced via the RIM process. These polyurethane moldings have excellent reactivity, demold properties (at a 30s demold), and good elongation and tear strength, and comprise the reaction product of an HDI prepolymer having an NCO content of 5 to 25%, a functionality of less than 2.3, and a monomer content of less than 10%, with an isocyanate-reactive component comprising b1) at least one relatively high molecular weight organic compound containing at least about two isocyanate-reactive hydroxyl groups; b2) at least one relatively low molecular weight organic compound selected from the group consisting of diols, aminoalcohols, and mixtures thereof; and b3) at least one relatively low molecular weight hydroxyl-based crosslinking compound containing no more than one aliphatic amine hydrogen atoms capable of reacting with isocyanate groups; in the presence of at least one catalyst.