TWO-COMPONENT, PRIMERLESS, URETHANE-ISOCYANURATE ADHESIVE COMPOSITIONS HAVING HIGH TEMPERATURE RESISTANCE

摘要

A two-component polyurethane composition has good shelf stability and the adhesive made by curing the same has good high temperature stability and no adhesion loss after high temperature bake. The base or prepolymer component containing a primary hydroxyl intermediate also has a sufficiently large excess of free isocyanate so that the ratio of free NCO groups in the prepolymer component to OH curative groups plus any amine groups in the curative component is generally from about 1.2 to about 2.0. The curative component contains a trimerization catalyst so that upon cure, isocyanurate units are produced. The system also contains molecular sieves, as well as phosphorous-type adhesion promoters.