MDI Based Flexible Foam A Status Report on World Developments

Moulded flexible polyurethane foam using hot-cure moulding technology with TDI as the isocyanate component was developed in the mid 1950's. The authors trace the development in the mid 1960's of HR or cold-cure foams which used TDI/MDI blends and more reactive polyether polyols. The logical next step was the introduction of All-MDI based, cold-cure flexible foams in the late 1970's. Much progress has been made since then, and the changes in processability which have led to better durability and greater comfort in seat cushions – both in the automotive industry and the high quality upholstered-furniture market are reviewed. Comfort properties are defined in terms of persons-sitting experience, and the load-bearing and hardness qualities required are defined to achieve good comfort levels. Environmental considerations are discussed with respect to the lower vapour pressures at normal processing temperatures given by MDI as compared with TDI. The current concern regarding the effect of CFC's on the atmosphere is discussed and ways in which the levels are being reduced in the All-MDI based foam moulding process are indicated. Cushions with dual and multiple hardness and pour-in-place techniques are discussed and the commercial experiences with the total range of All-MDI based foam systems – worldwide – is reviewed.