Foam XPS board

The extruded foam polystyrene is the most used material for thermal insulation.
During the last years the extrusion lines for XPS boards have undergone to important engineering modification to be adapted to the environment friendly blowing agents which are substituting the traditional CFC and HCFC gases, the use of which is now strictly limited. We have therefore equipped our research department with a complete new storage and distribution system which can operate with 3 different flammable or not flammable gases at the same time. In this way we had the opportunity to make long and extensive trials on our single and twin screw extruders, modifying not only the mechanical characteristics (alternative gases require different pressures and temperatures), but mainly the configuration of the extruder requested by the process, i.e. screw L/D, screw geometry and in particular geometry and length of the mixing zone, position and numbers of bores for gas injection and number of heating/cooling zones.
The configuration of our lines for this technology depends on the outputs required by the customers: if the output is lower than 400 kg/h we use a slow co-rotating twin screw extruder, if it’s higher, up to 2000 kg/h, we use the Tandem system because it’s necessary to separate the first part of the process (melt, mixing and expanding gas injection) into the primary extruder with a high revolutions number from the second part (cooling of the melted material) into the secondary extruder with low screw revolutions.