Abstract: A polyurethane foam produced by the reaction of a polyisocyanate and a polyether polyol in the presence of a catalyst, a cell regulating agent and water as a blowing agent, the polyether polyol of which consists of a halogenated polyether polyol (I) of the general formula: ##STR1## wherein x is a number of 0 to 7; y is a number of 2 to 3; A is a saturated or unsaturated, brominated polyol residue having a number of functional groups of y; R is hydrogen or an alkyl group having 1 to 5 carbon atoms and (II) a polyether polyol having a number of functional groups of 2 to 8, a weight ratio of the added amounts of propylene oxide and ethylene oxide within the range of about 75 to 95/25 to 5 and a hydroxyl number of about 20 to 100 mgKOH/g, whereby a weight ratio of (I) to (II) is about 95 to 25/5 to 75 and the amount of water is about 5 to 20 parts by weight against 100 parts by weight of the polyol component.

Abstract: Polyetherpolyols useful in preparing rigid polyurethane foam excellent in dimensional stability and inflammability. These polyetherpolyols are obtained by reacting alkylene oxide with compounds containing active hydrogen atoms, part or all of which comprise the reaction product obtained by heating the distillation residue secured as a byproduct in the distillation process of a crude polyisocyanate in the presence of (1) water, alcohols and/or amines and (2) hydroxides or oxides of alkali metals or alkaline earth metals and/or monoalkanolamines.