No. 39 - PUR Thermal Insulation

Polyurethane rigid foam insulation for use in both the refrigeration and building/construction markets was in its infancy in 1955. A Plastics Technology article in February 1960 identified refrigerators as the first big application for PUR thermal insulation. It suggested that residential and commercial construction was a second application that could become significant. In fact, by 2002, construction used 790 million lb of rigid PUR insulation and appliance insulation used 264 million lb, according to the Alliance for the Polyurethane Industry (API) in Arlington, Va.

In December 1961, Plastics Technology reported on one of the first “urethane-foam walls,” or metal/foam sandwich applications: “The prefabricated metal panels insulated with a new type of PUR plastic foam lowered construction costs of two new curtain-wall buildings at Sylvania Electronics at Waltham, Mass. Two-thirds of the exterior walls, or about 50,000 sq ft, are porcelainized steel panels laminated over a 3/4-in. core of Foamthane, a freon-blown polyurethane foam insulator recently introduced by Pittsburgh Corning Corp.” Because of their insulating efficiency, the foam panels were half as thick as fiberglass or polystyrene foam insulation.

Over the next 20 years, advances included growth of felt- and foil-laminated boardstock, made possible by continuous lamination machinery introduced from Europe in the early 1960s. Also new were isocyanurate foam insulation boards, which have greater heat and flame resistance and now constitute 75% of the rigid PUR foam market.

Other key developments were the introduction of frothing technology by DuPont in 1961, which allowed for faster cavity filling and lower and more uniform foam densities. Another was the emergence of polymeric MDI at ICI, which eliminated the prepolymer step needed with the older TDI-based systems.

The introduction of the mechanical, self-cleaning, airless spray gun by Gusmer in the 1960s provided processors with the benefits of higher throughput and reduced costs by eliminating solvents and atomizing the liquid stream without compressed air.