Crosslinkable Hot Melt Adhesives for Flexible and Structural Bonding
In view of the excellent adhesion to various substrates, flexibility and impact resistance properties, polyurethane adhesives, either two-part liquid or one-part moisture curing, have been widely used in structural and semi-structural bonding applications. These systems often require either a long fixturing time or, in many cases, external energy such as heat or induction to accelerate the cure. In recent years, polyurethane hot melt adhesives have been introduced eliminating the requirement for long fixturing times. However, certain limitations have restricted their wide spread acceptance, particularly in applications requiring a combination of processing and performance characteristics. We have recently designed a series of reactive polyurethane hot melt adhesives for structural as well as flexible bonding applications, with unique combinations of properties such as fast setting speeds, low viscosity good flexibility, and thermal and UV stability.