Patent ID: 8372892

Claim:
A method of forming a rigid polyurethane foam attached to an automotive part having an open cavity, comprising mixing a polyisocyanate component with a polyol component in the presence of at least one catalyst for the reaction of a polyol with a polyisocyanate and a blowing agent, dispensing the resulting mixture onto an automotive part defining an open cavity and subjecting the mixture to conditions sufficient to cause the mixture to cure to form a foam having a bulk density of 3 to 40 pounds per cubic foot (48-640 kg/m 3 ) that is adherent to the automotive part, wherein (a) the polyisocyanate component contains at least one compound having a plurality of free isocyanate groups, (b) the polyol component contains isocyanate-reactive materials that have an average functionality of at least about 2.3 and includes at least one polyol and, (c) the volume ratio of the polyisocyanate component to the polyol component is no greater than 5:1 and no less than 1:5, (d) the ratio of isocyanate groups in the polyisocyanate component to the number of isocyanate-reactive groups in the polyol component is from about 0.7:1 to about 1.25:1; (e) the blowing agent consists of a carbamate of an alkanolamine or a mixture of water and a carbamate of an alkanolamine; and (f) the cream time of the mixture is less than 2 seconds.