The concept of the planetary roller extruder (PRE) has been used in PVC compounding since the 1960s. While the general process technology in the plastics industry has constantly developed further, the processing and compounding methods for PVC have remained almost unchanged in many aspects for decades. In this context, ENTEX has been pushing a modern approach for the PVC compounding with the planetary roller extruder for several years now.
The goal is to skip the charge-wise premixing of PVC formulations as dry blends and to implement a continuous direct extrusion process instead.
The production of a dry blend is a time-consuming, discontinuous process that requires a great deal of energy and staff. Therefore a simplification or even the complete omission of this procedure offers a large savings potential.
PVC directly extruded without premixing and intermediate product
Since the 1980s, the planetary roller extruder has been intensively further developed with regard to its mechanical design and process control, which has opened up many new fields of application for this type of machine. In particular, the improvement of the tempering performance due to the use of modern manufacturing processes, system structures with several modules and the development of lateral feeding and degassing mechanisms, enable processes today, which were not conceivable on this type of machine for a long time. This allows to question the traditional processing methodology of PVC with the result, that it can also be realized in a direct extrusion process without dry blends as an intermediate product.
Direct compounding as a continuous process:
The raw PVC is dosed into the extruder without pre-stabilisation. The stabiliser system is added in parallel as a separate component. The diffusion process of the liquid components into the PVC grain, which takes place in the discontinuous process in an internal mixer with the addition of heat and mechanical energy in the form of impact and friction effects, is accordingly omitted. Instead, the grain of the solid components is mechanically broken up in the PRE immediately after entering the planetary roller module by rolling over and friction. The separately added liquid components are pressed into the grain by rolling over the powder at the same time.
For technical questions, please contact our service department or you are welcome to use the following contact form.
L-WE 30 - a new extruder generation for the laboratory scale
The modular extruder system of ENTEX has been complemented with the Pharma Laboratory Extruder of size 30. This means that the advantages of the planetary roller extruder - absolute temperature control and suitable mixing of active substances, low-shear thin-layer rolling-out, large surface exchange - can now also be applied in material-critical areas. With this, ENTEX allows now to process also material quantities of several hundred grams per hour.
Did you know that we have registered a new property right?
The ENTEX system is enriched by a further element – ERMO (degassing reaction module) is a world innovation that further enhances the efficiency and versatility of the ENTEX planetary roller extruder.
This latest addition to the modular system of ENTEX offers a significantly increased process chamber volume in comparison to the conventional cylinder assembly of the respective series.
It has been developed specifically for degassing applications. Here, free large-scale process surfaces and generously dimensioned flow cross-sections are decisive. ERMO maximizes these aspects without significantly changing the size of the extruder.
But the advantages of ERMO can also be used for the addition of fillers with particularly low bulk density – also here, the largest possible free cross sections are needed for the supply of such materials.
Another example of application are processes in the field of reactive extrusion. For their successful execution an extension of the dwell time or an enlargement of the reaction surface or of the volume are required.
Like all other components of the modular ENTEX system, several ERMOs can be used in series or at separate positions of a production line – in addition, there are various supplementary options such as side feeder, injection and degassing openings.
For more information about ERMO please contact our service department or you are welcome to use the following contact form.
One Planetary roller extruder replaces 28 twin screws
with respect to the gaps between the kneading elements!
Enclosed find our PDF with more information.