Ambient moisture-curing polyurethane adhesive

A process for making a one part, ambient moisture-curable polyurethane adhesive which is dispensed for use from a substantially hermetically sealed container, said process including the steps of

• reacting about 30 to about 50 weight %, based on the total weight of the adhesive, of a polyol selected from the group consisting of polyether diols, triols and tetrols based on propylene glycol or ethylene oxide-capped propylene glycol and mixtures thereof and having an average molecular weight of about 1000 to about 10,000, with an organic polyisocyanate having a functionality greater than 2, at a ratio of isocyanates equivalents to polyol equivalents of about 3:1 to about 15:1, for a sufficient time to form a polyurethane reaction product including an isocyanate-terminated prepolymer and unreacted isocyanate (polyol-isocyanate reaction);
• admixing with said reaction product at least one additive selected from the group consisting of thixotropic agents, fillers, antioxidants, plasticizers, solvents, pigments, adhesive promoters, UV stabilizers and defoaming agents, said additive containing a sufficient amount of total free water to provide a ratio of water equivalents to polyol equivalents of about 0.2:1 to about 2:1, whereby said free water reacts with unreacted isocyanate in said reaction product to extend the molecular chain of said polyurethane and provide hard segments therein (water-isocyanate reaction);
• allowing said water-isocyanate reaction to proceed until a predetermined amount of unreacted isocyanate remains to produce an isocyanate-terminated polymer adhesive containing unreacted isocyanate;
• and
• introducing the resulting adhesive into a substantially hermetically sealed container.