COMPOSITION, METHOD AND UNIT FOR THE CONTINUOUS PRODUCTION OF A FOAMED POLYMER SHEET AND RESULTING SHEET

摘要

The present invention describes a process and respective installation for continuous production of foamed polymeric sheets by extrusion, another object of the invention being the development and use of polypropylene-based formulations comprising linear polypropylenes and branched polypropylenes. The installation includes four stages: a first stage of extrusion foaming, in which a foaming agent, either of a chemical or physical nature, in the latter case introduced in supercritical conditions, is mixed with the polymeric mass melted previously in the first stages of the extruder, the material expanding exactly at the outlet of the lips of the planar extrusion head; a second stage of calibration and cooling of the foamed sheet, in which the expanded plastic material is cooled by contact in a system of vacuum calibrators and by contact with water in a cooling bath; a stage of collection of the foamed panel; and a final stage of cutting of the foamed sheet, defining the final dimensions thereof.