Bio-based, solvent-free and low-viscosity polyester polyol for 2K PUR

 
Bio-based solvent free low viscosity polyester polyol was prepared from raw material that can be either 14C or mass-balance certified. The basic properties such as OH number, viscosity and Tg are a close match to the ones of an oil-based resin that is often used as a modifier of high-solids acrylic polyols in 2-component PUR topcoats or DTMs or as a stand-alone binder. The material was tested in comparison with the standard oil-based material in a hybrid acrylic-polyester 2-component PUR topcoat formulation. No significant difference was found in wet film and application properties. The dry film appearance and mechanical properties are also a very close match. The durability of both coatings was confirmed with accelerated weathering tests monitored with gloss and color change measurement as well as IR and SEM inspections of the surfaces. Water condensation and NSS tests of both topcoats in a system with an e-coat primer don't show any significant difference. The same is true for the chemical resistance of the materials. The novel polyester polyol can thus be used as a drop-in replacement of the conventional oil-based resin and represents the next step towards sustainable coatings