Polyurethane foam


BASF’s Micro-Springs polyurethane foam enables the construction of a one-piece, drop-in unit that consists of millions of tiny polymer springs that deliver the same performance in comfort, feel and durability as furniture made with conventional eight-way, hand-tie large metal spring systems.


The difference is that Micro-Springs foam technology could cost as much as 35 percent less than current traditional furniture components. In addition, tests have shown that people find the material more comfortable.


Standard sofas and upholstered chairs use flexible polyurethane foam in tandem with metal spring systems for cushioning. The metal springs portion is typically installed by hand. This step in the production process involves aligning the metal springs, hand-tying the coil with eight strands of polyester twine and attaching it to the frame. Taking anywhere from 15 to 60 minutes depending on the size of the piece of furniture, this part of the manufacturing process is time consuming and inefficient.


A key measurement for how a spring feels and its durability is Hysteresis loss, which assesses the response force of the spring during compression (sitting down) and relaxation (standing up). A curve is created that depicts the response force in both directions. In a perfect spring, the curves for compression and relaxation would be exactly the same. Because there are no perfect springs, Hysteresis is expressed in terms of the difference between the two curves, or the Hysteresis loss.


In a recent evaluation, a base of eight-way, hand-tied springs typically used in furniture units with no foam cushion had a hysteresis loss of about 16 percent compared to the proposed polyurethane-only value of 20 percent. However, when a foam cushion was added to the base of springs, the composite hysteresis loss reached 36 percent. The composite hysteresis loss curve for a combination of BASF’s Micro-Springs polyurethane and the standard cushion matched the 36 percent result of conventional hand-tied spring and foam cushion construction.