Currently, the bonding process in the footwear manufacturing process is one of the steps with the highest impact on the environment, mainly due to the use of organic solvents in the most common adhesive formulations, as well as VOC emissions during the application of some surface treatments such as halogenation, and the use of some hazardous chemicals.
Therefore, the main challenge nowadays is to introduce innovative, resource-efficient materials and processes to reduce or eliminate the use of water, energy and hazardous chemicals, and minimise emissions and waste. Furthermore, applying sustainable-by-design principles based on life cycle assesments will contribute to reduce the footwear environmental impact and its carbon footprint, in addition to the development of sustainable footwear.
For these reasons, in order to reduce the environmental impact of the footwear bonding process, INESCOP is focusing on different approaches within the life cycle of the shoe where adhesives and surface treatments are involved. On the one hand, research is being conducted on the development of reactive hot melt polyurethane adhesives to simplify the bonding process and reduce the impact by synthesising polyols with renewable resources such as biomass waste and carbon dioxide emissions. On the other hand, studies are being developed in the application of plasma technology as a more efficient and sustainable surface treatment before the bonding stage to improve the adhesion properties of materials. Finally, the functionalisation of adhesives to facilitate disassembly at the end-of-life recycling stage is also under research.
Co-authors: M.P. Carbonell Blasco, C.B. Mateu Romero, E. Orgilés Calpena, F. Arán Ais