| 摘要 |
There is described a method for producing an expanded polystyrene sheet wherein a mixture of polystyrene and other additives is extruded in a tubular shape which is calibrated on a mandrel, cut and wounded in coils, the method being firstly characterised in that the tubular is cooled down on the external side downstream the extrusion opening when the expansion of the polystyrene has begun, and secondly in that the mandrel dimensions are chosen so that the ratio between the mandrel diameter and the extruder opening diameter is between 4,3 and 4,4. <??>The expanded polystyrene sheet according to the invention has a structure formed with a surface portion of prefixed thickness (0,7-2mm) having closed cells and a remaining portion of major thickness having a deformed, open cell structure. Said sheet also has good liquid absorbing characteristics and therefore can be advantageously used for producing trays for food products which can release liquids. In such a production the sheet is preferably coupled at one of its surfaces to a compact material film. <IMAGE> |
