POLYURETHANE ADHESIVE FOR A SURFACE TREATMENT-FREE FIBER REINFORCED PLASTIC

摘要

A two component type polyurethane adhesive is provided for fiberglass reinforced plastics which requires no cleaning, preparation or treatment of the surface, and the like. The curative component is a nitrogen-free liquid polyether or polyester in an amount such that in association with a urethane prepolymer component containing free NCO groups, the ratio of the free NCO groups in the prepolymer component to the OH groups in said curative component is at least 1.2 and desirably at least 1.35. Such high NCO/OH ratios have unexpectedly been found to provide good adhesion and especially good humidity adhesion and peel strength adhesion to fiberglass reinforced plastics or metal surfaces which are free from any surface treatment.