Improvement of the Anticorrosive Properties of Coatings by Decreasing Stress Magnitude

 
Stress phenomena in organic coatings have a profound effect on coatings and are known sinceb decades. Unfortunately these phenomena are not well known from most specialists in the coating sector. What are the origins of stress in organic coatings? What are the consequences of stress in organic coatings? What is the effect of coating components on stress? Can stress influence adhesion and cohesion of organic coatings? This paper will give an answer to these questions. The importance of understanding and measuring stress became evident with accumulated facts about its role in coating degradation. This is also supported by the fact that many coatings used today (e.g. thermosets) are more susceptible to developing high stress than traditional ones (e.g. alkyd paints). It is now quite clear that stress can affect coating adhesion and/or cohesion and provokes delamination and/or cracking. Since the development of stress is involved in practically all stages of coating life (film formation, exposure to various climatic conditions) it is also influenced by the coating composition. Its measurement is tremendously important for a better understanding of coating behaviour but also for the improvement of coating formulations and performances, especially durability. The know-how about the stress in organic coatings as well as the methodology to measure it (the CoRI stressmeters) exists within CoRI since many decades. Extensive research has been carried out at CoRI during many years in order to better understand all the parameters which can influence the stress development in organic coatings.