New technologies for viscoelastic PUR foams.

Viscoelastic (VE) flexible urethane foams are growing in popularity for pillows, mattresses, and furniture due to their special properties. First, they conform to body contour while yielding gradually to pressure and body heat, and thereby distribute contact pressure over the largest possible surface. Second, they retain a "memory" of the body and do not rebound immediately.

Bayer MaterialScience, Pittsburgh, recently unveiled two new developments in its Bayfit Memory VE-PUR foam formulations. One involves more cost-effective production of watertight VE foam padding with a spray-on elastic skin for gardening and camping. The aim is to replace the current waterproof coverings of flexible PVC that are applied to VE foams post-production and require high levels of plasticizers that can leach out and lead to gradual embrittlement.

Application of a "high-grip" Baytec Reaktiv sprayed elastomer coating during manufacture of the foam permanently seals the Bayfit Memory padding without need for a vulnerable film covering. One method involves spraying the elastomer into an open mold before the VE system is poured. The thickness of the skin can be varied over the surface of the product. Alternatively, an elastic grade of Bayfit can be used to backfill the mold after the VE foam is cured. Coating hardness can be tailored from extra-soft (35 Shore A) to extra-hard (60 D).

Bayer has also developed new all-MDI VE foam formulations. These are more convenient for manufacturers than previous systems that utilize both TDI and MDI. According to Bayer, there is no compromise in properties. Tel: [phone] * PTDirect: 468PT

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