| 摘要 |
<p>The previously known co-extrusion heads are suitable only for processing thermally stable polymer melts, such as for example PP and PE, because they can be moulded into tubes on manifold sleeves having the known heart-shaped groove distributions. Thermally sensitive polymers, such as for example PVDC and PET, but in particular rigid PVC, cannot be processed in the known co-extrusion heads, since the material would stagnate in the transitional area of the open manifolds and decompose within a short time due to the effect of heat. The co- extrusion head according to the invention also permits the processing of, for example, rigid PVC by a combination of the mandrel support principle, by which a rigid PVC strand introduced into the extruder head at the top is formed into a tube, with the heart-shaped groove principle, by which material strands of another material introduced into the interior of the rigid-PVC tube are processed, for example to form a barrier layer tube and to form adhesion promoter layer tubes. <IMAGE></p> |
