| 摘要 |
<p>A zero pressure device is composed of either a microcellular or homogeneous polyurethane made by reacting an organic polyisocyanate with at least three polyols, a monomeric polyol of 2 to 3 hydroxyls having a molecular weight of less than 250, a polyester polyol of 2 to 3 hydroxyls having a molecular weight of 800 to 3000 and a polyether polyol of 2 to 3 hydroxyls having a molecular weight of 4 to 7000. When the zero pressured device is a run-flat ring for a tire-wheel assembly, it has an average density of 60 to 65 pounds per cubic foot and 30 to 42 pounds per cubic foot when it is a tire.</p> |
