Flexible, Water-Resistant Urethane Coatings for Ferrous Surfaces on U.S. Army Corps of Engineers' Dams

摘要

The overall purpose of this study is to evaluate formulations for an extremely tough, water-resistant, urethane base coating which will withstand the punishment and erosion of turbulent waters carrying sand, ice, and other debris. The objective of the short-term phase of the study documented in this report was to assess ambient-air-curing elastomeric coatings to identify those with tensile strength and elongation properties and excellent water resistance. More than 200 coatings were prepared, based on the most promising prepolymers, polyols, and diisocyanates. Films of the coatings showing the highest tensile strength were subjected to a hydrolytic stability test, the result of which indicated losses in tensile strength of up to 50 percent. Series of coatings were formulated and prepared based on polyester polyols and polyether polyols, and the resulting coatings were subjected to the hydrolytic test after curing for 2 weeks at ambient temperature. The result indicated that the test cycle was too short for conclusive determination of hydrolytic stability. The data in this study was obtained from ambient-temperature-curing urethane elastomeric coatings containing solvents. Coatings based on polyester polyols have a maximum tensile strength of up to 2800 psi; for those based on polyethers, the maximum tensile strength was 1800 psi.