NEW DEMANDS FOR FOAM EXTRUSION WHEN USING CO_2 AS DIRECT GASSED FOAMING AGENT

摘要

Starting in Germany in the late 90ties, typical foaming gases for XPS insulation board like 142/R22 were substituted by more environmental friendly gases. Even these substitutes are going to be banned. As with Butane as foaming gas the required mechanical properties can not be achieved, XPS producers have to change to CO_2 as foaming gas. Whilst this situation is well known in Germany, the rest of the EU will follow in the near future. CO_2 is an inert gas and therefore not easy to mix into the polymer melt. Moreover, the foaming reaction is not endothermic, so the expanding CO_2 does not remove energy from the inside of the foam board. Due to this, the extrusion of insulation board is in a change period. This infects the process itself as well as the machine technology. SMS Folientechnik has developed new extrusion technologies to meet the demands of CO_2 as foaming gas.