Rigid polyurethane foams

Abstract

A process is provided for the preparation of rigid forms which comprises the step of reacting an organic polyisocyanate with an isocyanate-reactive material in the presence of a blowing promotor being an isocyanate-reactive cyclic compound of formula: ##STR1## wherein Y is O or NR.sup.1 wherein each R.sup.1 independently is a lower alkyl radical of C.sub.1 -C.sub.6 or a lower alkyl radical substituted with an isocyanate-reactive group; each R independently is hydrogen, a lower alkyl radical of C.sub.1 -C.sub.6 or (CH.sub.2).sub.m --X wherein X is an isocyanate-reactive group which is OH or NH.sub.2 and m is 0, 1 or 2; and n is 1 or 2; with the proviso that at least one of R.sup.1 or R is or comprises an isocyanate-reactive group; and in the presence of an inert insoluble organic liquid which is present as the dispersed phase of an emulsion or a microemulsion and in the presence of a metal salt catalyst characterised in that the isocyanate-reactive material comprises a polyether polyol of average nominal functionality of 2 to 6 and a number average equivalent molecular weight between 1000 and 2000.

Dependencies are inferred from the claim text.