Polyurethanes prepared from TERRIN™ polyols are initially darker in color but are more color stable than polyurethanes prepared from conventional polyols.
A coating formulation based on 4,4’-diphenylmethanediisocyanate (MDI) was used to evaluate performance of TERRIN™ polyols when substituted for conventional polyols.
Figure 1 is a composite image showing the tested coatings after 500 hours at 100°C (thermal), 500 hours exposure to a high-intensity xenon-arc UV light (Weather-Ometer® tester), or in the dark at ambient temperature (control).
No cracking, chalking, or other obvious surface degradation was observed visually but some color changes occurred. The DEG-adipate, Castor oil, and Poly-G polyether based coatings were initially light in color but darkened moderately with thermal exposure and very dramatically with UV exposure. This behavior is expected for coatings based on aromatic isocyanates such as MDI. In contrast, the TERRIN™ polyol-based coatings are amber initially, due to the color of the polyols, but little or no color change occurs on UV exposure.