| 摘要 |
A process for preparing extruded polymer foam products wherein surface defects are minimized is disclosed, wherein the polyethylene wax is added to the resin mixture or during some intermediate step of the process to reduce or eliminate the occurrence of surface defects, wherein the cells of the extruded polymer foam is free of halo-carbon blowing agents. There has been a movement to replace conventional halo-carbon blowing agents in favor of purportedly more environmentally safe halo-carbon free blowing agents such as carbon dioxide, nitrogen, argon, water, air, nitrogen, and helium. However, these halo-carbon free blowing agents, in particular carbon dioxide, have higher foaming rates and higher volatility leading to greater surface defects in the extruded foam. The polyethylene wax containing extruded polymer foam products are characterized by a generally smooth substantially defect free surface and contain a majority of closed cells which are free of any trapped halo-carbon blowing agents.
|
