Two Component Room Temperature or Induction Curable Structural Adhesives for Automotive Applications

Two-component epoxy adhesives that cure at room temperature but are responsive to induction heating offer tremendous processing flexibility in the manufacture of hemmed closure panels. Using a two-component, hemmed closure panels can be induction heated to quickly cure the adhesive. Since two-components are generally very reactive, lower induction temperatures can be used and panel handling strength will still develop within minutes. Also, if panel deformation due to induction heat is a concern, or if spot induction coils are being used, two-component epoxy adhesives build strength with time at ambient temperatures, allowing parts to be handled within 3-4 hours after hemming.

Experiments described here will illustrate the differences between single-side coils and L-coil induction heating systems. Other induction experiments will show the sometimes large differential between metal skin temperature and the temperature actually seen by the adhesive in the bondline. The performance features of three epoxy room-temperature curing two-part adhesives which are also induction curable will be discussed. The evaluation of bonds made under a variety of cure conditions with various draw lubricants will be used to show the versatility of these two-part adhesives and suggest their suitability for numerous automotive bonding applications.