Vanillin as low-temperature isocyanate-blocking agent and its use in one-component aqueous coatings

Abstract Mainly because of the high sensitivity isocyanate group to atmospheric moisture, it is blocked with a blocking agent for many applications and thus kept as inert possible at room temperature (Zhang et al. in Langmuir ACS J Surf Colloids 37:12705, 2021, Meier-Westhues Polyurethane: Lacke, Kleb-und Dichtstoffe, Vincentz Network, Hannover, p 36, 2007). When exposed temperature, protective unblocks, reacts reactant that was previously present together (Meier-Westhues Kleb- und 2007, Goldschmidt Streitberger BASF handbook on basics coating technology, pp 96–99, Many substances which are used today agents have toxicological concerns or unblock temperatures, limits their application areas (Guillem Parra Blocked polyurethane compositions using new agent, method manufacture uses thereof: European patent application, 2019, https://data.epo.org/publication-server/document?iDocId=6506253&iFormat=0 ). In this work, vanillin presented an effective deblocking low temperatures compared similar structures. The process from hexamethylene diisocyanate trimer (HDI-trimer) followed by means IR-spectroscopic measurements different thermogravimetric analysis. Temperature-dependent oscillation rheometer suitable measuring onset qualitatively tracking unblocking process. combination results draw conclusions about existing mechanism. comparatively enables formulation HDI-trimer modified sulfonate groups vanillin, dispersed aqueous phase then reacted OH-functional binders. Deblocking subsequent reaction binder IR spectroscopy, mechanical properties films examined. Vanillin therefore toxicologically harmless isocyanates production crosslinkers one-component water-based coatings (Arya Adv Tradit Med (ADTM) 21:1, 2021).