A premix made from polymer, pigment and dispersion aid is fed into the extruder via volumetric feeder. This is generally produced in “batches” in mixers in a preceding processing step.
In this variant of masterbatch production, the polymer is first plasticized. The pigment, the filler material and, where necessary, the dispersion aid are then incorporated into the melt downstream through one or two side feeders. The individual formulation components are supplied through gravimetric feeders.