Polyurethane polyols and coatings thereof having reduced viscosity

摘要

The present invention relates to a film forming composition, a method of forming the composition, and application of the composition to coating formulations which provide a cured coating having acid rain resistance. A film-forming polyurethane polyol composition comprises a reaction product of an n-functional isocyanate (wherein n is a number ranging from about 2 to about 5) with at least one diol or triol or mixtures thereof and a compound containing isocyanate-reactive functional groups, preferably a monofunctional alcohol or thiol. The low viscosity polyurethane polyol of the present invention is typically crosslinked/cured using a melamine to produce a cured coating which is highly acid etch resistant as well as having other desirable physical-mechanical properties. The coating compositions have improved flow characteristics compared to compositions containing polyurethane polyols prepared without the monofunctional alcohols or thiols. The invention also relates to mixtures of nonfunctional polyurethanes with polyurethane polyols.