Low volatile isocyanate monomer containing polyurethane prepolymer and adhesive system

Abstract

In one aspect the invention is a composition comprising a prepolymer which is the reaction product of di(isocyanatophenyl)methane or a polymeric di(isocyanatophenyl)methane having an isocyanato functionality of about 2.1 to about 3.0 with a mixture of one or more diols and one or more triols wherein the ratio of isocyanate equivalents to hydroxyl equivalents in the reaction mixtures used to prepare the prepolymer is from about 1.2 to about 1.8 and the ratio of diol to triol where the diisocyanate is a di(isocyanatophenyl)methane in the reaction mixture is from about 5:1 to about 1:1. and where the isocyanate is a polymeric di(isocyanatophenyl)methane is from about 8:1 to about 4:1; wherein the prepolymer could further react with an isocyanate reactive monofunctional compound. The prepolymer herein has an isocyanate content of about 0.5 to about 1.5 percent by weight, a free isocyanate monomer content of about 1.0 percent by weight or less as measured by high pressure liquid chromatography. These prepolymers can be used in many applications including adhesive, sound dampening sealer and coating and especially in making adhesives or adhesive systems with a low content of monomeric isocyanate to bond together similar or dissimilar substrates such as metal, glass, ceramics, plastic and painted steel panel.

Dependencies are inferred from the claim text.