Icosyanate-Free Polyurethane Coatings

Polyurethanes (PUs) are made by reacting two components, one of which has two or more hydroxyl (OH) groups (diol or polyol) while the second has two or more isocyanate (NCO) groups. Unfortunately, not only is the isocyanate component a powerful irritant, but sensitized subjects can suffer severe asthma attacks and even death when exposed to trace quantities that are well below permissible exposure levels. The hazard is particularly significant to those that apply PU paints, as this process involves spraying both components onto a surface where the cross linking reaction occurs. Clearly, it would be beneficial to replace PUs with less hazardous alternatives. However, the less-hazardous coating chemistries tried to date either offer insufficient performance, cure too slowly or are too expensive. In this project, TDA Research, Inc. (TDA) will demonstrate a new route to making PU coatings that will have the same structure and performance as current coatings, but which will not require the use of isocyanate precursors.

A successful project will result in a cost-effective drop-in technology that allows the elimination of isocyanate from current two-part polyurethane coating formulations without the need for reformulation and requalification. This will allow a rapid transition to the market. Eliminating reactive isocyanate groups from PUs will clearly eliminate toxicity and industrial health and safety problems associated with current polyurethanes, and will reduce high cost in health and workers’ compensation benefits that today arise from worker sensitization. Furthermore, TDA’s proposed approach may reduce both the cost of the PU coating and the VOC emissions.

TDA’s chemistry could be easily employed to provide an isocyanate-free alternative to many existing two-part PU paints with limited reformulation and testing efforts. Therefore, TDA’s approach is expected to be widely applicable to many applications that today use two-part PUs.

Urethane coatings are one of the fastest-growing sectors of the worldwide paint and coatings industry. Despite their relatively high cost, their excellent durability, resistance to corrosion and abrasion, pleasing optical properties and flexibility make urethane coatings suitable for a range of high-performance applications. Dominant markets include automotive refinishes, wood finishes and high-performance anticorrosive coatings. The worldwide market for automotive refinish coatings was valued in 2007 at $5.12 billion and that of field applied, room temperature- cure industrial maintenance coatings were valued at $3.0-$4.5 billion. Even a modest 1% penetration of this market would represent $100M revenues from the technology resulting from this project.

TDA’s chemistry is expected to outperform that of other non-isocyanate polyurethanes because (1) it will be significantly cheaper to make the resins required to formulate the coating; (2) it will constitute a drop-in technology and require no reformulation when used to replace the components of a current two-part PU coating; and (3) it is expected to provide a faster room-temperature cure.