Compsn. (I) contg. polyols, polyisocyanates with an isocyanate functionality of 3.0 +/- 0.7 and a diisocyanate content less than 20 wt.% (w.r.t polyisocyanate), and opt. monofunctional break-down agents. Also claimed are (i) the use of (I) for the prepn. of synthetic foams from non-returnable pressurised containers contg. a compsn. (Ia); (ii) the prepn. of (I) by reacting the polyisocyanate with the polyol and break-down agent via a single- or two step process; (iii) moisture-cured, single component synthetic foams prepd. from (Ia); and (iv) two component synthetic foams prepd. from (Ia) and a polyol.
