Abstract: Methods comprising: providing an aromatic polyisocyanate and a polyol; and reacting the aromatic polyisocyanate and the polyol in the presence of a blowing agent and a catalyst to form a rigid polyurethane foam; wherein the blowing agent comprises water and a hydrocarbon having 3 to 8 carbon atoms; and wherein the polyol comprises a mixture of two or more polyether polyols according to formula (1): wherein each R independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and n represents an integer of 0 to 5; the mixture of polyether polyols having a mean functionality of 4.5 or more; and wherein the mixture of polyether polyols comprises 50 to 70% by weight of a compound of formula (1) wherein n=0 is and 30 to 50% by weight of a compound of formula (1) wherein n?1; and wherein the mixture of polyether polyols comprises 2.5% by weight or more a compound of formula (1) wherein n=4, all percentages by weight based on the mixture of polyether polyol.

Abstract: The amount of aldehyde emitted from a polyurethane and molded articles made of a polyurethane is reduced. The reduction of aldehyde emissions from polyurethanes is achieved by including a hydrazine compound as an aldehyde-scavenger in the polyol component of the polyurethane-forming reaction mixture. The hydrazine compound is used in an amount of 0.05 to 3.0 parts by weight, based on 100 parts by weight of the polyol mixture. Aldehyde emissions from molded polyurethane articles are reduced by including a hydrazine compound in the mold coating material in an amount of from 0.1 g/m2 to 10 g/m2.