Silicones

A customised solution for any challenge

When it comes to successfully manufacturing and compounding silicones, there are several decisive factors: achieving desired viscosities quickly, optimising dwell time control, taking advantage of reactive extrusion processes, and ensuring high-performance degassing.

• Achieving desired viscosities quickly

  Among other things, silicone manufacturing requires mixing two or more basic components with sharply different viscosities. Here, the Planetary Roller Extruder is able to offer optimum results on account of the special geometry of its mixing chamber and its operating principle, which is based on a continuous rolling mill. Depending on the unit size, it is possible to have as many as 48 kneading gaps – this corresponds to approx. 50 individual steps in the conventional dual-roller mill that is traditionally used in the silicone sector.

• Optimum dwell time control

  The modular design is the key, as separate process zones, coupled with precise temperature control and monitoring, make it possible to optimise dwell time control to facilitate the reactions necessary to integrate large volumes of fillers. Fillers with low bulk densities can be mixed in without difficulty. Over 50% fumed silica with a bulk density of less than 20 grams per litre is feasible.

• Reactive extrusion processes offer a tangible advantage

  Unique: By offering as much as ten times the internal energy exchange surface area available in conventional mixing aggregates like twin-screw extruders, the Planetary Roller Extruder is ideal for chemical reactions. Reactants are able to complete their reactions even over a relatively short distance in the process. The key to this is the system’s geometry with rotating planetary spindles.
  The reactants often have a very low viscosity, for example of only 1 – 50 mPa-s. The Planetary Roller Extruder efficiently mixes these with the polymer and the filler, each of which have significantly higher viscosities.

• High-performance degassing

  By-products and other volatile substances created by the reaction can be efficiently evacuated. It is possible to create process zones with a vacuum of less than 1 mbar in the Planetary Roller Extruder to efficiently degas the extrudate. This also offers other benefits – for example, it allows the extrudate to be stored, because any by-products that might otherwise trigger undesirable reactions have been removed from the material. Odours and possibly toxic gases are also removed, making a valuable contribution to quality control while increasing work safety. The self-contained continuous manufacturing process inside the Planetary Roller Extruder makes this possible, eliminating the need for the batch processes that are otherwise common in silicone production.

• Customised solutions that are sure to impress

  Depending on the customer’s specific requirements, various additives can be fed into the ongoing process, including colourants via fluid injections or solid materials using gravimetric dosing systems with coupled side feeders. The Planetary Roller Extruder’s modularity makes it extremely flexible and excellently suited to satisfying the individual requirements of the customer and their process. This ensures an attractive ROI.