Patent ID: 6924321

Claim:
A process for the production of a rigid polyurethane foam by reaction of a mixture of (a) at least one organic polyisocyanate with (b) a polyol composition comprising (b1) from 0 to 95 percent by weight of a polyol compound having a functionality of 2 to 8 and a hydroxyl number of from 200 to 800 and (b2) from 5 to 100 percent by weight of at least one polyol compound having a functionality of 1 to 8 and a hydroxyl number of from 20 to 200, wherein the weight percent is based on the total amount of polyol component (b), and (2) is obtained by alkoxylation of at least one initiator molecule of (b2a) wherein (b2a) is H 2 N—(CH 2 ) n —N(R)—H Formula (I) where n is an integer from 2to 12, and R is a C 1 to C 3 alkyl group; or (b2) is a hydroxyl-tipped prepolymer obtained from the reaction of an excess of a polyol obtained by alkoxylation of an initiator of (b2a) with a polyisocyanate; or (b2) is (b2g) a blend selected from polyols obtained by alkoxylation of an initiator of (b2a) or hydroxyl-terminated prepolymers obtained from polyols based on initiators (b2a); (c) in the presence of a blowing agent; and (d) optionally additives or auxiliary agents known per so for the production of rigid polyurethane foams, wherein the amount of polyol (b2) is present in an amount such that the curing time is substantially equivalent to a similar reaction mixture containing a volatile tertiary amine urethane catalyst where the reaction mixture with a polyol of (2) contains at least 10 percent by weight less of such volatile tertiary amine urethane catalyst.