Improvements in or relating to polyurethanes

Polyurethanes are produced by reacting an organic polyisocyanate with a hydroxyl-containing product prepared by adding to a compound containing a plurality of active hydrogen atoms first a 1,2-alkylene oxide having at least 3 carbon atoms, then ethylene oxide, and then a further 1,2-alkylene oxide having at least 3 carbon atoms and either the same as or different from the first one. The compound with active hydrogen atoms may, for example, be water, ammonia, hydrazine, an alcohol or phenol or a carboxylic acid. All the specific examples use trimethylolpropane. Preferably, the polyethers contain 1-25% by wt. of ethylene oxide based on the total oxyalkylene content. An antioxidant may be incorporated into the polyether. Polyisocyanates mentioned may be di- or tri-and may be monomeric or low molecular weight polymers. All the examples use mixtures of 2,4- and 2,6-tolylene di-isocyanate. The polyurethanes may be rigid or flexible, and foamed or not. Conventional gas producers, catalysts and other additives may be used.