Ko-kneader

Extrusion compounders such as the Buss Ko-Kneader have been used for mixing phenolic resins. It is elaimed that they produce in some respects a better produet and are more eeonomical to use than mill-mixers. 

Fig. 25. Ko-kneader intensive compounding extruder [Courtesy Buss. AG] (a) Schematic diagrams of slotted screw and barrel pins, (b) ko-kneader with barrel in open position...

The Ko-Kneader developed by List in 1945 for Buss AG in Germany, is a single-rotor mixer-compounder that oscillates axially while it rotates. Moreover, the screw-type rotor has interrupted flights enabling kneading pegs to be fixed in the barrel (12). 

Other common continuous mixers involve substantial modification of single and twin screw extruders, aimed at improving distributive mixing capability in particular, and leading to the development of continuous mixers such as the Transfermix (50) and the Buss Ko-Kneader (51). Another approach in continuous mixer development is to transform batch mixers into continuous ones. Thus, the roll-mill can be converted into a continuous mixer by feeding raw material on one side and continuously stripping product on the other side. In addition, the Banbury mixer was imaginatively transformed into the Farrel Continuous Mixer (FCM) by Ahlefeld et al. (52), and, later, two similar continuous mixers were developed by Okada et al. (53) at Japan Steel Works and by Inoue et al. (54) at Kobe Steel. 

Figure 92. Granulation equipment for plastics, (a) Extruder-granulator, (b) Ko-kneader, (c) plastificator and calender...

Depending on the nature of the filler distribution within the matrix, the morphology of the nanoeomposites can evolve from the so-called intercalated structure where a regular alternation of the layered silicates and polymer monolayers is observed, to the exfoliated (delaminated) structure where the layered silicates are randomly and homogeneously distributed within the polymer matrix. The easiest and technically most attractive way to produce these types of materials is to knead the polymer in the molten state with a modified layered silicate, such as montmorillonite. Compounding on different machines, such as a Buss ko-kneader or mills, still produces essentially the same morphology in the resulting nanoeomposites. 

Co-Kneader (Ko-Kneader) having Reciprocating Scre v and Pin Barrel -Parrel Continuous Mixer -List Continuous Mixer -Ring Extruder. 

The performance of two compounds was compared one made from 65 wt% ATH and 35 wt% EVA with 28% vinyl acetate content and a second from 60 wt% ATH, 5 wt% organoclays, and 35 wt% EVA with 28% vinyl acetate content. Both compounds were prepared on a BUSS Ko-kneader (46-mm screw diameter, L/D 11). Both were investigated... 

Whilst most early work was carried out in solution French workers have developed solid state methods where the anhydride is added to the rubber either on a 2-roll mill or, as later developed, in an extrusion compounder such as a Buss Ko-kneader. A typical reaction in such a device took 8-15 minutes at 200-250°C. 

Typical examples of the single screw kneader are the Buss Ko-kneader and the Baker-Perkins Ko-kneader. 

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