New Amine-Based Catalysts for Low-Density, Water-blown Microcellular Foam Used in Shoe Soling Application s

摘要

One of the major problems in making low-density microcellular foam for shoe soling applications is dimensional stability. Most formulators reach a density reduction limit near 0.30g/cc. Below this density, the dimensions of the molded soling component often change noticeably after demolding. The main cause of this problem is high closed-cell content in the foam. As the density is reduced, there is less polymer mass to support the dimensions of the closed cells, making them more susceptible to distortion caused by the pressure of the trapped internal gas. One way to reduce dimensional instability in low-density foams is to create some mechanism for cell opening, which allows the cell gas to equilibrate with atmospheric pressure and thus not affect the cellular volume. The mechanism presented here is the use of “cell-opening” catalysts that allow the cell windows to drain and open by slowing the gelling reaction during foaming. Using these new “cell-opening” catalysts with surfactants that will not overly restrict cell drainage is the key to this proposed mechanism. An example of the use of these catalysts and surfactants in a polyester-based insole shoe sole system will be given. The reduction of the demold time of soling components using this new technology will also be shown versus the previously offered generation of cell-opening catalysts. The reduction of skin delamination also associated with density reduction will also be discussed through the use of these new cell-opening catalysts.