New Technology for Viscoelastic Foam

Abstract

The production and use of slow recovery “viscoelastic” polyurethane foams have increased rapidly over the past few years. Their unique performance characteristics, which include shape conformance, vibration and sound damping, and energy and shock absorption, make these the foams of choice for many diverse applications such as pillows, mattress toppers, automotive trim, sports and medical equipment, and ergonomic cushions and pads. These diverse applications require a wide range of foam grades with tailored performance properties. New polyol and formulating technology is being developed to meet the increased demands for improved processing, wider grade latitude and improved performance properties of viscoelastic foam. This paper reports the results of systematic experimental design studies that were conducted in the laboratory to help develop this technology. A key advance is the development of polyol compositions that enable the production of high quality, soft viscoelastic foams at 100 index and above. This eliminates processing inconsistencies associated with low index foaming, and yields foams with superior performance characteristics such as improved compression sets, reduced discoloration, and finer cell structure with improved feel. The design studies also identified formulating routes to optimize key foam performance features such as low resilience, slow but complete recovery, maintenance of slow recovery characteristics with use, reduced temperature sensitivity, good airflow, and good strength properties. The results of machine foam studies will be presented along with additional foam performance results.

Preparation of Molded Viscoelastic Polyurethane Foam for Pillow Applications

“…The foam samples from the present investigation showed a rebound resilience value of 3%, whereas the value for the commercially available sample was 5%. The time taken by the foam to return to 95% of its original height after being compressed for one minute to 25% of its initial height was used to indicate the memory character of the specimens [11]. In this aspect also the foam developed in the present study was found to be better than its commercially available counterpart.…”

Engineered polysaccharide alpha‐1,3 glucan asisocyanate‐reactivecomponent in viscoelastic polyurethane foams

“…The SEM images in Figure 8 show that the reference VE foam has mostly open cell structure, with cell windows completely open. Having an open cell structure with ruptured windows is a desirable property for VE foams, ensuring that the foam is fully compressible and dimensionally stable 45–52 . VE foams containing alpha‐1,3‐glucan polyol dispersion also have uniform cells with open cell structure.…”

Effect of vegetable‐based polyols in unimodal glass‐transition polyurethane slabstock viscoelastic foams and some guidance for the control of their structure–property behavior. I

“…Since the introduction of the line of VE products into the market, there have been numerous reports in scientific journals and conference proceedings on some of the features of VE‐related foam materials and their fundamental properties; these have all focused on the use of polyols derived largely from petroleum feedstocks 17, 30, 32–43. (Glycerin, which could be from natural or synthetic origins, is used in the manufacture of some VE polyols.…”

“…Two us also previously addressed many of the formulation variables that influence the mechanical behavior of largely petroleum‐based unimodal‐ T g VE foams and their temperature dependence 34, 36. Kageoka et al,33 in addition, provided some more detailed studies on the loading rate dependence in conjunction with the temperature variability of VE foams in view of the strong importance of these coupled variables to the actual in‐use behavior of such products.…”