PROCESS FOR PROCESSING EXPANDABLE POLYMER PARTICLES AND FOAM ARTICLE THEREOF

摘要

ABSTRACT OF THE DISCLOSURE Process for processing expandable polymer particles e.g. polystyrene (EPS) that eliminates the maturing step between the pre-expander and molding steps. The expandable particles are first over pressurized with gas, e.g. air, carbon dioxide, nitrogen, and mixtures thereof, at a pressure between 500 and 8000kPa and a temperature between -20°C and 130°C for 15 to 7200 minutes to create a gas pressure in the particles. Using the gas pressure in the particles, pre-expanding the particles with a heating medium, e.g. steam at a temperature between 100°C and 120°C and at a pressure ranging above atmospheric pressure and below the gas pressure in said particles, i.e. 50 to 200kPa for 5 to 120 seconds. The pre-expanded particles are air dried in the pre-expander while holding a positive pressure in the particles; are optionally transferred to a pressure silo; and then are transferred to a molding machine where the gas pressure in the particles is used to form a foam article.