Process for the preparation of cellular synthetic resins by the isocyanate polyaddition process by means of a stable emulsion containing a propellant, and these emulsions

The invention also provides a process for the preparation of cellular plastics by the polyisocyanate polyaddition process by reactinga) organic and / or modified organic polyisocyanates withb) at least one higher molecular weight compound having at least two reactive hydrogen atoms, and optionallyc) low molecular weight chain extenders and / or crosslinkers in the presence ofd) blowing agents,e) catalysts,f) auxiliaries and / or additives, wherein as the blowing agent (d) low-boiling sparingly (a) to (c) or insoluble fluorinated or perfluorinated hydrocarbons having 3 to 8 carbon atoms, sulfur hexafluoride or mixtures thereof, and this in the formative components (a), (b), mixtures of be emulsified from (b) and (c) or (a) and (b), and storage-stable, blowing agent-containing emulsions of the aforementioned blowing agents (d) and the structural components (a), (b) or (b) and (c).