Compounding systems for Antistatic Compounds

Due to the very high volumetric and surface resistances of polymers such as polystyrene, polycarbonates and polyolefins, electrostatic charges can only dissipate very slowly. The effect known as triboelectric charging, where a single contact is enough to electrostatically charge the surface, means that components often leave the shaping machine already statically charged.

Such charging can have unpleasant or even dangerous consequences for users and processors. Electrostatically charged plastics attract dust, adhere to each other, are difficult to print, and discharge at high field strengths by sparking, which although physiologically harmless, can have sufficient energy to ignite explosive media.

Typical applications

Antistatic additives can be used to reduce surface or volumetric resistance to the point where charges can dissipate sufficiently quickly. This is achieved by using permanently effective or migrating antistatic masterbatches of various types. The migrating substances require a certain ambient humidity in order to develop the desired effect. In addition to conductive carbon-based materials such as carbon black and graphite, conductive polymers such as polyether polymers or polyaniline are playing an increasingly important role among the permanently effective substances due to their low intrinsic colouring. These allow the materials to be coloured as desired and form an ion-conducting network in the base matrix.

Compounding requirements

The preparation of these antistatic concentrates is just as broad a field as the additives used and their modes of action. Conductive properties in the end-product are targeted and often combined with other characteristics, such as colouring. The enormously wide variety of requirements, which can range from high loadings and different states of the aggregates, to shear and temperature-sensitive raw materials and end products, requires a universally applicable system. The Buss Kneader is regarded as the system with the best all-rounder qualities. And thanks to its system design freedom, the Buss Kneader responds specifically to changing requirements in the process zones with application-targeted configurations.

In this way, optimal results can be achieved in terms of quality and throughput. Furthermore, easy accessibility through hinged or retractable housings allows extreme product changes with high availability. Thanks to broadly based Buss process expertise, the Buss Kneader is therefore a safe and future-oriented choice for antistatic compounds production.

Elektrostatic sensitive electronics can be protected with antistatic compounds.

Typical plant layout for antistatic compounds

BUSS compounding systems for antistatica offer the following specific benefits

  • Easy access to process parts
    Easy access to process parts is guaranteed because Buss Kneaders feature a split-barrel design with a uniquely wide opening angle of 120°. This allows fast and easy screw adaptations within minutes, without removing the screw or barrel, thus assuring fast product changes and higher yields.

  • Flexible configuration of process section
    Screw elements, barrel liners and kneading pins are easily exchangeable components quickly accessed by opening the Buss Kneader’s split barrel. They can all be changed without removing the barrel or screw shaft.

  • High filler loadings
    Filler loadings up to 90% are possible with Buss technology thanks to 2 or 3 feed openings, separate gravimetric feeding of filler, removal of trapped air by back venting, and excellent conveying efficiency. The moderate shear rates allow perfect handling of the highest viscosities at such high loadings.

  • Intensive distributive mixing
    The Buss Kneader achieves intensive distributive mixing because the combined rotation and axial motion of the Kneader screw generates extensional flow, a large number of shear interfaces, and cross channel mixing.

  • Intensive mixing at low specific energy input
    Buss multiple-flight Kneaders of the latest generation achieve better mixing at 15-40% lower overall specific energy input. This is because of an increased number of mixing cycles according to the needs of each individual process section. The energy for melting and mixing is provided almost entirely mechanically and optimally dissipated according to the imparted shear rates.

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