Two package waterborne urethane systems

This article is an extensive review of the literature on two component urethane systems that use water as a carrier. It generally covers the period from 1985 through 2000 with special emphasis on patent references since 1993. It includes both ambient temperature cured and baked systems containing unmodified and modified isocyanate building blocks. The main criterion for inclusion into this paper was that the finished urethane group containing polymer reaches its ultimate molecular weight after it is applied to a substrate, so that traditional latex-type materials are not emphasized. The paper describes the raw materials and chemistry used in this field and presents some of the factors that must be considered to make this unique chemistry industrially feasible. The major concern is formulating, mixing, and applying the systems in a manner that limits the water reacting with the highly active isocyanates to avoid defects from generated carbon dioxide. The review also discusses some of the end use areas where two component urethanes have been commercially applied. (C) 2002 Elsevier Science B.V. All rights reserved.