Thermal debonding on demand for wood coatings via nitrocellulose-based primer
Thomas S. Hofer, Albert Rössler, Oliver I. Strube
Abstract
Wood is an ever more demanded material for sustainable construction. However, to perform accordingly, most of the material has to be coated, usually with a petroleum-based polymeric lacquer. Due to difficult removal of the coating layers, coated wood is usually discarded at its end-of-life, resulting in lost value and environmental issues. To tackle this challenge, we aim to establish an integral recycling process, based on the principles of circular economy. As a first step, we herein introduce a novel technique for efficient and feasible separation of wooden substrate and coating at end-of-life. To this end, we developed a thermally triggerable primer based on nitrocellulose (NC) which enables debonding on demand specifically for coating layers on wood. The debonding mechanism is triggered at temperatures of 160–170 °C and results in complete loss of adhesion, while having no negative impact on the coating during use. The effect can be applied on large substrates with ease. It can also be used site-specifically which leaves adhesion of non-primed areas fully intact. Additional mechanistic investigations show that decomposition of NC is observed mainly at the interface between primer and coating.