The Use of Pentanes As Blowing Agent in Rigid Polyurethane Foam for Lamination

Pentanes tend to be considered as long-term alternative blowing agents for rigid polyurethane foams. They are environmentally friendly, non-toxic and economically feasible. A major drawback of the use of pentanes is their flammability and their relatively high thermal conductivity, compared to CFC-11. As pentane processing techniques have improved considerably, safety can now be insured at a reasonable price. In this paper the overall performance of pentane blow laminates in terms of processing, insulation value, mechanical properties and flammability is demonstrated. The ageing characteristics are compared to those of CFC-11 blown foams. The low vapour pressure of both n-pentane and cyclopentane is shown to induce condensation effects. The consequences of condensation in terms of thermal conductivity and dimensional stability are discussed. The problem of pentane solubility in the polymer matrix and its influence on the long-term foam performance is addressed. Possible solutions are presented.