HIGH PERFORMING POLYURETHANE COATING COMPOSITIONS AND PROCESSES FOR MAKING THE SAME

摘要

This invention relates to polyurethane coatings formed from prepolymers made by reacting polyisocyanates with long chain polyols having an average functionality of greater than 2. The resulting prepolymers have equivalent weights greater than about 250 grams per equivalent and preferably greater than about 350 grams per equivalent. An excess of polyisocyanate is reacted with the polyol component at an equivalent ratio of greater than 4:1 equivalents isocyanate per equivalent of polyol. Excess polyisocyanate is then removed from the prepolymer.PPThe resulting polyurethane prepolymers are chain extended with compounds having active hydrogen atoms such as water, amines or short chain polyhydroxy compounds, e.g., diols to form the resulting coatings.