Process for the preparation of cellular polyurethanes

摘要

The prodn of cellular polyurethanes (PU) comprises reacting (a) polyisocyanate(s) and/or modified polyisocyanate(s), (b) high-mol wt cpd(s) with at least two reactive H atoms, and opt (c) low-mol wt chain extenders and/or crosslinkers in the presence of (d) acetal(s) as blowing agent, (e) catalysts and opt (f) additives etc. Also claimed is the same process for the prodn of (i) PU mouldings with a compact surface zone and a cellular core, and (ii) flexible PU foam.