2.2 In-depth study of drying solventborne alkyd coatings in presence of cobalt-free driers

摘要

As a result of potential reclassification of cobalt-based alkyd driers, many studies have been conducted to find suitable alternatives as primary driers. A systematic investigation on the oxidative drying of solventborne alkyd coatings with commercial cobalt-free driers was performed, i.e. Nuodex Co 10 Neo, as a reference and an iron-based drier (Borchi OXY-Coat) and two manganese-based driers (DriCAT 2700F and Nuodex Drycoat). This work investigates how these driers influence the molecular network development and mechanical properties of the final films from the moment of application to full drying. High spatial resolution NMR profiling allows tracing the depth-resolved crosslinking during drying, and is used for the first time in conjunction to time-resolved ATR-FTIR and standard methods like Beck-Koller (BK) drying test, Konig hardness and DMA. We have found correlations between the drying pattern of driers and properties such as the drying rate, the overall and depth-resolved crosslink density and hardness development.