| 摘要 |
Process for the preparation of rigid foams comprising 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: <CHEM> wherein Y is O or NR<1> wherein each R<1> independently is a lower alkyl radical of C1-C6 or a lower alkyl radical substituted with an isocyanate-reactive group; each R independently is hydrogen, a lower alkyl radical of C1-C6 or (CH2)m-X wherein X is an isocyanate-reactive group which is OH or NH2 and m is 0, 1 or 2; and n is 1 or 2; with the proviso that at least one of R<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, wherein the isocyanate-reactive material comprises a polyol or polyol mixture of average nominal functionality between 2 and 3 and number average equivalent molecular weight between 31 and 750. |
