The Effects of Water as a Partial Blowing Agent for Rigid PUR and PUR/PIR Foams

A preliminary evaluation of HCFC 123 and HCFC 141 b demonstrated that they appeared to be technically viable CFC-11 replacements only after substantial reformulation. Partial water blowing was proposed as a possible short/medium term solution to the decreasing availability of CFC-11 as a consequence of the Montreal Protocol. In both polyurethane refrigeration and lamination products partial water blowing was shown to be a practical possibility up to a CFC-11 reduction of 50%. Slight deterioration in thermal efficiency was compensated for through formulation optimisation. Preliminary work on the type of formulations used to produce PUR/PIR foams in the USA boardstock industry showed that a 25% reduction of CFC-11 was so far achievable without loss of mechanical and fire properties.