process for the production dipannelli expanded polystyrene osimile material device for execution of the process eprodotto obtained

摘要

A process for manufacturing expanded polystyrene panels includes the following stages: (a) Preparation of pre-expanded panels of polystyrene by extrusion and simultaneous injection of propellent agent into an extruder fitted with an extrusion die of suitable type and in particular fitted with means allowing for good mixing of the molten polymer with the propellent agent and means allowing for uniform cooling to the best value of the temperature of the expandable plastic mass before exit from the die. (b) Conditioning of said panels at room temperature or at whatever temperature higher than room temperature, provided it is such to prevent the panels from undergoing either dimensional variation or deformation due to internal stress or true expansion. (c) Forming of pre-expanded panels into a mould-box by means of heat furnished by convection by a hot fluid the ratio between internal dimensions of the box and measures of pre-expanded panels being such that 60 percent at least of the volumetric increase given to the mass is affected to their average increase in thickness.