Easy, user friendly control of hardness is of high interest for the production of flexible polyurethane foam. There are several ways to influence the hardness. Reduction of hardness and obtaining a softening effect usually has only limited impact on other foam physical properties. However, an increase in hardness is not readily possible without undesirable changes of other foam physical properties in flexible polyurethane foams. There are different ways to increase hardness in flexible polyurethane foams. For example it is possible to strengthen the three dimensional network of the polyurethane foam. Usually a better cross-linking leads to an increased hardness. But normally this also gives rise to a more closed cell structure of the foam. This change in porosity is responsible for an undesired loss of breathability and a different long-term behavior of the polyurethane foam. In order to create a foam hardener which does not affect other foam physical properties, Evonik has put a lot of effort into understanding the hardening effect of foams. This has led to the development of a tailor-made, highly sophisticated foam hardener additive for flexible foam. Therefore we have synthesized a new ORTEGOL~® product to combine low use level with a significant increase in hardness without significant impact on other foam physical properties.
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