Waterborne Coatings Direct-to-Metal (DTM) Applications

By Raymond S. Stewart, Ramesh Subramanian

Waterborne coatings have promised much and have been accepted very cautiously over the last 30+ years in the industrial coatings market. Surface tension sensitivities and narrow application windows have hindered acceptance in some segments of the market. Advances in high and ultra-high solids technologies have competed successfully in many areas of this market. As a result, the formulator has had to wait for new developments in waterborne resin technology. Solventborne polyurethane types have been available for many years.

The continuing surge forward in the development of more environmentally friendly coatings has produced significant advances in polyurethane dispersion (PUD) waterborne chemistry. It is the authors’ belief that newly developed PUDs should be considered an important part of the formulator’s toolkit. This article focuses on advances made in the area of oxidatively curing PUDs which typify the rapid developments in waterborne polyurethane chemistry.

This curing mechanism finds its precedent in solventborne alkyd technology and has been adapted for use in waterborne resins.