Adhesive bonding is an attractive alternative to welding that offers car manufacturers the possibility to select from a broad range of lightweight materials to be joined. However, current methods require energy-intensive curing at very high temperatures that can be detrimental to components made of dissimilar materials. The POWDERBOND (Developing powder coatings for contact curing of structural adhesives for vehicle bonding applications) project was supported by the EU with the aim of developing a new powder coating system with an integrated catalyst for low-temperature curing. POWDERBOND partners developed a low-temperature contact-cure resin-catalyst formulation whose curing speed can be controlled by the catalyst concentration. They also identified a low-temperature powder coat and investigated three different routes to incorporate the catalyst. Tests showed that enhancing surface roughness of the powder coat improved bond strength, a parameter further investigated during optimisations. The desired cure speed (45 min) and depth (0.5 mm) was ultimately achieved at a temperature as low as 70 °C. This low-temperature adhesive bonding formulation addresses many of the current limitations of bonding methodologies. It reduces processing time and energy consumption. It also enables adhesive bonding of dissimilar materials, being specially formulated for both chassis and component assemblies. POWDERBOND technology will enable car manufacturers to reduce the carbon footprint of their activities while delivering vehicles with lower fuel consumption and fewer emissions. Overall, it will improve the competitive position of EU small and medium-sized enterprises in the supply chain for current and future automobiles.
Adhesive bonding, automotive industry, low-temperature curing, POWDERBOND, powder coating