Patent ID: 7635723

Claim:
A method for producing a rigid, closed-cell polyurethane foam comprising: forming a reaction mixture comprising: a Component A comprising: (a) and isocyanate and at least one alkyl alkanoate as needed; and a Component B comprising: (b) at least one polyol having a hydroxyl number of from about 150 to about 800 and being selected from the group consisting of polyalkoxylated amines, polyalkoxylated ethers, and polyester polyols, wherein all of said at least one polyols make up from 50% by weight to 100% by weight of all polyols in the reaction mixture, and at least one alkyl alkanoate as needed and (d) 0.5% to 4% water by weight of component B; wherein said at least one alkyl alkanoate blowing agent is present in an amount of from about 1% by weight to about 12% by weight of the reaction mixture and wherein said at least one alkyl alkanoate makes up more than about 80% by weight of all blowing agents in the reaction mixture, and curing the reaction mixture to form a rigid, closed-cell polyurethane foam having a closed-cell content of at least 85%, having a free-rise density of from about 1.3 lbs./ft 3 to about 4 lbs./ft 3 , and exhibiting a volumetric shrinkage of less than 10%, and wherein the gas in the cells of the foam contain more than about 40% by weight CO 2 and alkyl alkanoate.