A newly developed selection tool for water-borne polyurethane coatings in direct-to-metal (DTM) applications considers factors such as application timing, surface preparation and degree of protection provided, Bayer MaterialScience reports.
The development and use of the selection tool was reviewed during the 2010 Metal Protection Through Coatings Technology Conference, taking place Oct. 19-20 in Pittsburgh. At the conference, Pete Schmitt, Bayer MaterialScience strategic technology manager for polyurethane coatings, presented “A Selection Tool for Waterborne Polyurethane Coatings for Direct-to-Metal Applications.” The presentation was co-authored by Margaret Kendi, associate research scientist, and Dr. Raymond Stewart, senior R&D scientist, at Bayer MaterialScience.
Schmitt provided an overview of the testing conducted in the study and findings on the performance of water-borne polyurethane coatings for DTM applications compared with commercially available coatings.
The study used a guide formula made with commercially available raw materials. Tests were performed to evaluate the physical properties of the formula, which was then compared wth the physical results of commercially available DTM water-borne coatings systems.
The commercially available waterborne coatings tested include a water-based acrylic coating, a solvent-based alkyd coating, and a solvent-borne alkyd primer. The guide formula used in the study was a one-component, oxidatively crosslinking polyurethane coating based on technology developed by Bayer MaterialScience LLC.
All coatings were tested for adhesion to various substrates, including cold-rolled steel, B952-treated (zinc phosphate) steel, B1000-treated (iron phosphate) steel, aluminum (mill), and chromium-treated aluminum. Humidity resistance (Cleveland condenser) and corrosion resistance (salt fog) tests were also performed on all coatings.
Schmitt said the study confirmed the performance strengths of water-borne polyurethane coatings in DTM applications. The coatings also are reported to offer low VOC content and effective performance in single-coat applications.
More information: www.bayermaterialsciencenafta.com.