Low-temperature curable adhesive for joining dissimilar materials

Welding is an important joining process that has been used extensively in the automotive industry to join two similar materials, usually metals or polymers, through melting and coalescence. Adhesive bonding can expand the range of materials to be joined, facilitating important decreases in fuel consumption and associated emissions. However, current methods require energy-intensive curing at very high temperatures. Further, the thermal conditions can be detrimental to components made of dissimilar materials.

A novel powder coating system with an integrated catalyst for low-temperature curing is under development with EU support of the project POWDERBOND. Application and assembly is envisioned to be compatible with current adhesive assembly methods and machinery. The technology will enable manufacturers to significantly reduce the carbon footprint of their activities while delivering cars with much lower fuel consumption and fewer emissions. Overall, it will foster a competitive position for EU small and medium-sized enterprises (SMEs) in the supply chain for current and future automobiles.

The team has developed a low-temperature contact-cure resin-catalyst formulation whose curing speed can be controlled by catalyst concentration. It is currently being optimised.

Scientists have also identified the low-temperature powder coat and are investigating three different routes to incorporate the catalyst. Tests show that enhancing surface roughness of the powder coat improves bond strength, a parameter to be further investigated during upcoming optimisations.

POWDERBOND low-temperature adhesive bonding technology will address many of the current limitations of established bonding methodologies. It eliminates the need for a high temperature curing oven, thus reducing processing time, complexity and energy consumption. It enables adhesive bonding of dissimilar materials, being specially formulated for both chassis and component assemblies.

Finally, bond properties will be improved relative to established methods and production is compatible with current production flow for minimal investment. Overall, the technology will make life much simpler for European SMEs while increasing their competitive position in a large global market sector.