Reactive polyurethane coatings

摘要

This invention is concerned with a process for producing microporous coatings comprising (1) mixing an NCO-prepolymer prepared from polyisocyanates with compounds containing at least two isocyanate-reactive hydrogen atoms with about 3 to 40% by weight, based on the NCO-prepolymer, of a substantially inert, non-migrating liquid organic compound miscible with said NCO-prepolymer as a plasticizer; (2) adding about 3 to 300 weight % of water, based on the NCO-prepolymer, into the NCO-prepolymer-plasticizer mixture to form a water-in-oil emulsion; (3) adding a polyamine in a quantity substantially equivalent to the isocyanate groups; (4) applying a coating of the water-in-oil emulsion to a substrate; and (5) hardening the coating by evaporating the chemically unbound water from said coating.