High Initial Strength with Long Open Time Reactive Hot Melt Adhesive, 2001 Hot Melt Symposium Proceedings

Ju-Ming Hung--Reactive hot melt adhesives (RHMs) are solvent free, one-part solids at room temperature. These materials are heated to their molten state prior to use, then pumped and dispensed onto construction pieces in a hot and tacky state. When the assembled substrates cool back to ambient temperature, the bond strength builds up rapidly due to the solidification of the adhesive. The RHMs then start to react with moisture absorbed inside the assembled pieces to form a highly crosslinked network. The cured adhesives show significantly better heat resistance than assemblies glued with conventional one-part hot melt adhesives. In a commercial assembling process, manufacturing cost reduction through improved production rate is highly desirable. Therefore, increasing the initial strength of reactive hot melt adhesives is one of the approaches to improve the manufacture production rate. However, in most cases, the open times of RHMs are reduced while the initial strengths of the adhesives are increased. Therefore, the application for large size assembled pieces is limited. In this paper, a new technology is described that has enabled a series of high initial strength of RHMs, with long open time characteristics, to be prepared and commercialized.