POLYURETHANE ADHESIVE FOR A SURFACE TREATMENT-FREE FIBER REINFORCED PLASTIC

摘要

A two component type polyurethane adhesive isprovided for fiberglass reinforced plastics which re-quires no cleaning, preparation or treatment of thesurface, and the like. The curative component is anitrogen-free liquid polyether or polyester in an amountsuch that in association with a urethane prepolymercomponent containing free NCO groups, the ratio of thefree NCO groups in the prepolymer component to the OHgroups in said curative component is at least 1.2 anddesirably at least 1.35. Such high NCO/OH ratios haveunexpectedly been found to provide good adhesion andespecially good humidity adhesion and peel strengthadhesion to fiberglass reinforced plastics or metalsurfaces which are free from any surface treatment.