As 2020 has come to a close, we would like to give an overview of the progress made in 2020. All technical partners in the DECOAT project have joined forces to develop and test novel triggerable additives. At the beginning of the project, different working principles of triggers have been postulated. NTUA and DEVAN have synthesized these additives, of which the debonding efficiency is now being thoroughly tested, both on standard textile and plastic substrates. Some fluorescent markers have been physically bonded to the trigger materials at NTUA, to optically monitor their coating and debonding behaviour by the newly developed absorption/fluorescence spectrometry system of IRIS and the POLO® technology of Fraunhofer IVV. The applied triggers are heat, steam or microwave, depending on the type of additive. The debonding technology of RESCOLL, based on heat application, has already proven to nicely decoat the textile and plastic substrates.
Polyester textile samples which were coated with the most used textile coatings (polyurethane, acrylic and PVC) could also be nicely debonded via a solvation process (CreaSolv®). Some plastic parts showed to be more difficult as the bulk material dissolves along with the coating, more fine-tuning of the solvent is needed in this case.
Partner CTAG has conducted studies for ABS and ABS/PC plastic parts showing how many times the bulk material can be recycled and which maximum recycling content and maximum coating residue is allowed to end up with material still fulfilling the specifications. These parameters are of utmost importance if one wants to create a circular use of the bulk material.
Optical monitoring of the triggerable materials and identification of the additives in the coatings constitute important tasks for the recycling process and are carried out by IRIS and Fraunhofer IVV. To this end, the strategy of incorporating fluorescent markers into the coatings is investigated. The fluorescence allows for monitoring and sorting with optical methods such as the POLO® technique or Hyperspectral Imaging (HSI).
Compatible fluorescent dyes have been identified and successfully integrated into various triggerable materials and resins. In case where the fluorescent markers are directly incorporated into the trigger particles, four crucial steps in DECOAT can be monitored: the trigger distribution in the coating, the coating thickness of the debonding layer, the sorting of the coated parts to the debonding process, and the debonding process itself. Parts containing these smart additives in the coating are studied in regard to feasibility and performance of the optical monitoring and sorting systems that are being developed.