| 摘要 |
<p>Styrene polymer foam that is more environmentally acceptable, capable of making foam insulation over a wide range of densities, decorative and does not require the modification of existing equipment for high pressure operation is prepared using a mixed blowing agent of carbon dioxide plus ethyl chloride and optionally a fluorocarbon to provide a foam having primary cells and secondary cells defined by the struts and walls. The method of preparation involves heat-plastifying the styrene polymer and adding to the heat-plastified polymer a mixed blowing agent of carbon dioxide, ethyl chloride and optionally a fluorocarbon under a pressure sufficiently high to prevent foaming; reducing the temperature of the mixture and reducing the pressure of the mixture as it is extruded to form the foamed product.</p> |
