ALTERNATIVE COMPOUNDERS | MACHINERY
Checking out alternatives
Increasing use of biopolymers and recycled resins is opening up opportunities for manufacturers of alternatives to twin screw compounding extruders. Mark Holmes reports
While the twin-screw extruder is the mainstay of most compounding plants, there are alternatives. Kneaders, single-screw extruders, multiple-screw extruders, planetary roller extruders and continu- ous mixers all have their advocates and machinery manufacturers can provide them for a multitude of compounding applications. However, choosing the optimal extruder for a compounding task and establishing the reasons why one particular type of machine is suitable for that application is not a straightforward process. “As independent experts, we are often confronted with precisely this question or the questions that derive from it,” says Hans-Ulrich Siegenthaler of Switzerland-based consultants Kneading Experts. “For example, are there methods to find the right compounding system for a specific application? We would say that there are and have been able to use these methods very successfully in many projects. We have developed a toolbox of methods [Com- pounding Analytics]. With it, process-technical and production-technical considerations, as well as
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economic requirements, can be recorded holisti- cally and targeted solutions found. Some machine manufacturers are also using similar approaches for their own purposes,” he says. Recycling pressures are helping to drive interest in alternative compounding options, according to Siegenthaler. “In many applications where different types of polymers have been used in the same component or in the same material – for example, multi-layer films for packaging – alternatives are being sought to make the products recyclable. The European Union has already initiated regulatory steps through the European Green Deal,” he says. “The specific property profiles of alternative extruders can provide particularly valuable services in this regard. Examples include the excellent heat dissipation possibilities of planetary roller extrud- ers, the sophisticated degassing solutions of ring extruders and the gentle handling of polymers and additives in continuous kneaders (co-kneaders).” Another growth area can be seen in the area of energy storage and power transmission, he says.
Main image: Demand for kneader extruders, frequently favoured for thermally sensitive processing such as grafting, is ongoing and solid, according to manufacturer Buss
October 2021 | COMPOUNDING WORLD 27
IMAGE: BUSS
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