Quantification and Modeling of Ambient Cure Solvent-based Epoxy-amine Thermoset Coating Cure and Vitrification

摘要

The next generation of coating binder technologies are defined by the rigorous demands/hurdles for ease of application, short, and long-term performance characteristics and the competition inherently present as a resistance to change from current technologies. The performance basis of polymer networks is achieved through the complex interplay between environmental conditions, potlife, film formation processes, cure kinetics, solvent evaporation rates, and polymer vitrification of the coating. The complexity of the combined process has not been modelled adequately with respect to solvent-based thermoset cure kinetics at varying degrees of conversion and solvent content during the physical state shift from applicable liquid coating to crosslinked glassy matrices. The vitrification of solventborne thermoset coatings being the critical point defining development and "setting" of these properties thereby disrupting the cure process, solvent evaporation rates, and potentially limiting mechanical, transport and adhesion performance. The physical state and the residual solvent type/content/concentration and location vary with binder-solvent interactions and the thermal affects from differing environments. Quantifying, understanding, and ultimately predicting the cure kinetics, solvent evaporation rates, and resulting pre-exposure state of varied formulation solventborne coatings is critical to the minimization of re-formulation and solvent package re-design costs. The difficulty lies in the complexity of coating formulation including binder, catalyst, pigment, and additive selection and their direct impact on cure, solvent evaporation, and vitrification processes. This research is focused on quantifying and understanding to accurately model the autocatalytic thermoset cure process in the presence of plasticizing solvent towards a method for streamlining re-formulation screening of thermoset coating materials. Important to our research is the successful incorporation of plasticizing, catalytic, and possible retarding effects of solvent(s).