The project is organized in 7 main tasks, the Task0 corresponding to the management and coordination of the project and the Task6 corresponding to the dissemination and valorization of the results.
The Task1 is devoted to the choice of the resins and flame retardants that will be used to develop the self-stratifying coating. Compatibility of the resins will be investigated using both the state of the art and the Hansen approach, allowing selecting the most appropriate two or three resins components systems to start the second task. On the other hand, depending on targeted applications, and based on standards, representative fire and weathering tests will also be defined.
The objective of Task2 is to manage to design some model self-stratifying coatings using in a first approach two resins for application on plastic (Polycarbonate) on one hand and on steel on second hand. In this task, the systems of resins/solvents selected in Task1 will be applied on both substrates. The degree of self-stratification of the coatings will be investigated mainly using FTIR-ATR and cross sections analyses (SEM and electron probe microanalysis -EPMA). A particular attention will be paid to the interface substrates-resin and adhesion tests will be carried out. The coatings developed in this task will be submitted to weathering tests (Task5) and the formulations will be adjusted depending on the results obtained, in order to manage to pass the tests.
The Task3 and Task4, based on successful systems developed in Task2, consist in designing self-stratifying coatings presenting flame retardant properties in order to respectively (i) fire retard PC substrate and (ii) increase fire resistance of steel substrate. For each system, FR intumescent systems identified in Task1 will be incorporated in one resin and the change of behavior in the self-stratification process induced by the filler will be studied. The dispersion of the flame retardant additive in the coating will be evaluated through EPMA cross section X-Ray mappings. Specific fire tests defined in Task1 (e.g. cone calorimeter, UL-94, LOI for PC and furnace tests for steel) will be carried out on the coated samples to evaluate the fire retardant properties of the coated polycarbonate and the fire resistance of the coated steel. In a second phase, the mechanism of action of these FR coatings will be investigated: the fire tests will be stopped at critical times and the degraded coatings will be analyzed using adapted technics such as for example TGA, solid state NMR, SEM. The interface between the substrate and the degraded coating will also be investigated through SEM cross sections analyses. In a third and last phase, the efficiency of the optimized systems will be compared to a PC fire retarded in the bulk using traditional flame retardant additive and in the case of steel structure to a traditional three-layers coating system (primer, intumescent coating and topcoat).
The Task5 will be dedicated to the study of the durability of the coatings developed in the previous tasks. Resistance to weathering (such as for example UV, humidity, water immersion, depending on the targeted application) is a key requirement of the coatings to avoid the need of a topcoat. Specific weathering tests, depending on the application and on the substrate (PC or steel) will be carried out on the coatings following standards. The ageing of the coating will be fully examined using adapted spectroscopic technics and depending on the results the formulations developed in Task2, Task3 and Task4 will be adjusted.