Pittsburgh, Pennsylvania - Three Bayer MaterialScience llc scientists have developed a selection tool for waterborne polyurethane coatings for direct-to-metal (DTM) applications, to help coatings applicators evaluate the available products and so select the most appropriate coating system for any specific application.
Application timing, surface preparation and degree of protection provided are just a few characteristics that applicators must evaluate, says an announcement from Bayer MaterialScience. The selection tool was described in a paper presented at the Metal protection through coatings technology conference, held 19-20 Oct. at the Sheraton Station Square hotel in Pittsburgh.
Presented by Pete Schmitt, strategic technology manager for polyurethane coatings at BMS, under the title "A selection tool for waterborne polyurethane coatings for direct-to-metal applications" and co-authored by his colleagues Margaret Kendi, associate research scientist, and Raymond Stewart, senior R&D scientist, the paper gave an overview of the testing conducted in the study.
He also presented their findings on the performance of waterborne polyurethane coatings for DTM applications compared with commercially available coatings for DTM applications.
The study used a guide formula made with raw materials readily available in the United States. Tests were performed to evaluate the physical properties of the formula, which was then compared with the physical results of commercially available DTM waterborne 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 Bayhydrol UH 2592, a one-component, oxidatively crosslinking polyurethane coating from Bayer MaterialScience.
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.
"The study confirmed that waterborne urethane coatings have superior performance properties over commercially available systems," said Schmitt.
He added that two key advantages of waterborne urethane coatings are their low volatile organic compound (VOC) levels and the effectiveness of a single coat of waterborne urethane compared with multiple coats of commercially available systems.
With the successful findings of their study on waterborne polyurethane coatings for DTM applications, the group plans to perform additional testing on other formulations.