Analysis of the Evolution of PIR Foams in the Context of the Phase Out of HCFCs

Abstract

PIR foams are known for their outstanding fire properties and for their good insulation performances. The fire behavior can be attributed to the aromatic structure of the isocyanurate ring and to the nonflammability of the blowing agent that is used nowadays.For environmental reasons, HCFC-141b will have to be phased out as of 01.01.2003 for the production of PIR laminates boards, in Europe and in the United States. This evolution represents a challenge for the producers as they need to find a high performance alternative in a relatively short period of time. As a major requirement, this alternative will have to maintain the properties of the PIR foams, notably the fire behavior and the k-value at a high quality level.Several blowing agent alternatives have been presented, and some of them have already been implemented in production plants.Among them, pentane is seen as a candidate for economical reasons, but because of its high flammability, its use shows some limitations. The *This revised paper was presented in its original form at the Polyurethanes EXPO nonflammable alternative HFC-365mfc/HFC-227ea has proven to be an interesting alternative to obtain a good insulation value and good fire properties.Besides, the existence of azeotropic blends between HFC-365mfc and the pentane isomers increases the degree of freedom of the system and makes the optimization process easier. When using the right combination of blowing agent, it is possible to reach an interesting compromise between the insulation characteristics, the fire performance and the cost of the system.An analysis of properties of PIR foams produced with the several alternatives will be presented in this paper.

Fire Phenomena of Rigid Polyurethane Foams

“…Since the pentane adds no more than 3–5 wt % to the overall weight and thus barely any fuel or increased EHC, the fire behaviour of a RPUF is determined mainly by the solid polymer and not by the gas phase [8]. Investigations of pentane- and HFC 365mfc-blown foams have revealed that they do not differ fundamentally from CFC-11- or HCFC 141b-blown foams in their fire behaviour [47,48].…”