AQUEOUS POLYURETHANE DISPERSIONS AND COATINGS PREPARED THEREFROM

摘要

The present invention is directed to two- and three-component aqueous polyurethane composition which are cured at ambient temperature and have excellent chemical resistance without reduction in abrasion resistance and flexibility. The two component system comprises a first component of a hydroxy functional aqueous polyurethane dispersion and phenoxy resin blended together, and a second component of polyisocyanate. The three component system comprises a first component of a hydroxy functional aqueous polyurethane dispersion, a second component of epoxy resin; and a third component of polyisocyanate. Generally, the mass of the epoxy or phenoxy resins is 1 to 50 % of mass of the polyurethane solids in the dispersion and the mass of the polyisocyanate is 50 to 200 % of the mass of the polyurethane solids in the dispersion. The two- or three-component polyurethane composition has a mass fraction of solids of preferably 10-50 %.