Rubber compounding extruder feed

Tag : compression molding machine

The benefits offered by the new KraussMaffei Berstorff system areespecially significant in the production of soft TPE-V types.
In many cases, soft TPE-Vs are produced using oil-extended EPDMrubber, which is rather difficult to pelletise owing to its stickysurface and because separating agents must be used.
* Precise rubber feeding - the single-screw extruder ensuresreliable feeding and pre-compounding of the rubber.
A pressure-based control system adjusts the extruder speed in sucha way that the downstream gear pump is always completely filled.
The gear pump is designed to achieve precise volumetric feeding ofthe rubber into the twin-screw compounding extruder.
* Compounding process - inside the twin-screw compounding extruder,the rubber is mixed with the thermoplastics material, and thecross-linking reaction of the rubber phase takes place to form theTPE-V required.
The phase morphology and the physical properties of the finishedTPE-V are determined by the configuration of the twin-screwextruder.
The first extruder section is designed for the compounding andmixing of the main recipe components, usually EPDM and PP, and forthe incorporation of additives and processing oils.
Dynamic cross-linking takes place in the downstream mixing zones ofthe extruder.
The last extruder section is used for vacuum degassing.
* Combination with internal mixer - the new system can also be usedwith an internal mixer.
In this case, rubber, fillers, plasticiser oils and additives arepre-mixed in the internal mixer and fed into the extruder in theform of strips.
With this solution, the twin-screw compounding extruder is merelyrequired to mix in the thermoplastics material and, if necessary,the cross-linking agent and to perform the dynamic vulcanisationprocess.
* More about TPE - owing to their superior material properties,thermoplastics elastomers (TPEs) are becoming increasinglyimportant, said KraussMaffei.
TPEs can be easily processed, dyed and recycled.
Component weight, energy consumption and manufacturing costs aresignificantly lower than with cross-linked rubber (e g, pure EPDM).