| Résumé : |
A moisture-cured polyurethane system using raw materials from Bayer MaterialScience was used to coat more than 35,000 square feet of piping and valves inside the Hammond Water Filtration Plant.
A moisture-cure urethane (MCU) coating is a one-component paint that consists of a polyisocyanate functional resin along with solvents, pigments, catalyst, and additives. The coating cures as the isocyanate resin reacts with ambient moisture after being applied to the substrate. Figure 1 describes the curing mechanism in more detail.
When the coating is applied to the substrate, solvent begins to flash off and the coating absorbs some of the ambient moisture. The isocyanate (R-NCO) reacts with that moisture to form an amine (R-NH2) and release carbon dioxide gas. The isocyanate then reacts with the amine to form a polyurea crosslinked network.
The use of an aliphatic MCU topcoat offers several advantages. For example, these types of coatings can cure at low temperatures, as long as ambient moisture is present. Also, MCUs are very surface tolerant and, because they are a one-component paint system, mixing errors between multiple components in the field are avoided. |
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High-build MCU coating innovation in ADHESIVES & SEALANTS INDUSTRY (ASI), Vol. 18, N° 3 (03/2011)
