Improvements in or relating to the manufacture of foamed polyurethanes

Foamed polyurethane materials may be produced by the reaction of an organic polyisocyanate with an organic polyhydroxy compound and not more than 2.5% of water based on the weight of polyhydroxy compound, heat from an external source being applied to the reaction mixture, thereby raising the maximum temperature attained within the foamed polyurethane to not less than 120 DEG C. In an example, a foamed polyurethane material is made by mixing a glycol/propylene oxide condensate with a mixture of tolylene 2 : 4- and 2 : 6-diisocyanates, water, triethylenediamine, N,N-dimethylphenylethylamine and a siloxane-oxyalkylene block copolymer and heating to 80 DEG C. by microwaves. The blend is then poured into a mould and further heated by infra-red radiation to a temperature of 140 DEG C. Suitable polyhydroxy compounds are polyesters, polyesteramides, polyethers and non-polymeric oxyalkylation products of active hydrogen containing compounds. Catalysts, blowing agents, fillers, flame-retardants and colouring matters may also be added.