In most cases today masterbatch (MB) comprises a concentrate of colorants, fillers, additives or other ingredients for cleanly and easily attaining specific characteristics needed for the end application. Since many of the ingredients are originally in powder or liquid form, they would otherwise be difficult to handle or require considerable processing outlay. This applies for example to nanoparticle incorporation in a safe environment, or combining several additives to attain a specific characteristics profile. After compounding the ingredients into masterbatches, metering and processing the resultant granulate is much easier for end users. Standard processing machinery can often be used instead of complex systems.
The name “masterbatch” is said to have originated in the times when the “Master” was responsible for mixing specific batch formulations containing particularly valuable and costly additives. This is exactly how masterbatch production is classified today: precisely metered mixtures are compounded with plastics or substrates into batches suitable for further processing. The master’s responsibility of former times is now taken by the masterbatch plant operator’s specialists.
There are basically three masterbatch compounding methods:
- In many cases the Premix process is used. All the formulation components are first premixed in the solid phase, often including polymers in powder form. The premixtures are then volumetrically dispensed to a Buss Kneader for compounding.
- In the split-feed process, polymer is fed to the Buss Kneader melting zone while additives are dispensed downstream, at several points if so required.
- The colour matching method, with separate feed of the primary colours, enables rapid hue adjustments for high-quality applications, and efficient colour changing.
Thanks to multiple feed points, the Buss Kneader’s specific capabilities really come to the fore in the following applications. Due to the operating principle, the enormous number of mixing cycles at moderate and uniform shear rates enables unsurpassed mixing efficiency with minimal polymer matrix content. As a side effect of the moderate shear rates, wear and tear is significantly lower than with other kinds of screw extruders. The modular design of the entire Buss Kneader line makes it easily adaptable to all requirements. Together with the widely based Buss processing expertise, the Buss Kneader is first choice for compounding filler masterbatches.
Buss Kneader technology
Laboratory Kneader MX 30