Werner & Pfleiderer Gmbh

Allunions-wissenschafts- Und Forschungsinstitut Fuer Synthetische Fasern

Nautschno-proisvodstvennoje Objedinenije 'plastmassy' Research Institute

Eberhard Uhland

Hans Wobbe

Heinz Herrmann

Hellmut Boden

Hans Werner

Larisa Alexeevna Nosova

Anatolij V Beljakov

Bernhard Stoehrer

Sijar N Nurmuchomedov

Jelena V Schinkorenko

Ivan M Vlasov

Eckart Pantzer

Elvina Z Bokareva

Garri I Faidel

Viktor V Terenko

Anton Fuerst

In the preparation and production of plastic materials by a continuously operating double shaft screw-type extruder, the efficiency of production often depends on good delivery of material to the extruder. In accordance with the invention for processing various types of plastic materials, a primary stage is mounted in a pressure-tight sealed manner on the housing of the extruder, the primary stage being formed by a vertical double conical container in which a pair of screw-type helices are rotatably supported and driven from above. The helices are connected to two replaceable feed elements at their lower ends so that delivery of material to the extruder is achieved without any intermediate dead spaces.

Process and apparatus for two stage treatment of plastic materials

A screw kneader for a plastic material in which a pair of longitudinal screws are rotatably mounted in respective bores for conveying plastic material through the kneader. The screws have spaced portions for advancing the plastic material from an inlet region to an outlet region and between the spaced portions is a section with reversed threads opposing plastic flow to effect mixing of the plastic material. The threads of the intermediate section are provided with openings to permit passage of up to 20% of said plastic material in the direction of advance. Transfer elements with helical threads connect opposite ends of the threads in the intermediate section with the threads of the inlet and outlet regions. The transfer elements of the two screws mutually engage one another to strip plastic material from one another and from the walls of the bores.

Screw kneader for plastic material having a controlling mixing section

A process for separating low molecular weight compounds from a crude polycaproamide melt comprises heat treating the melt in vacuo with superheated steam, in an extruder having a plurality of degassing zones, under precise conditions of temperature, pressure and configuration, such that the occurrence of side reactions and dehydration of the melt are substantially eliminated, the molecular weight of the polymer during the heat treatment in vacuo, during transport and subsequent processing remains substantially unchanged, a residual content of low molecular weight compounds of .ltoreq.1.8% is achieved, and the operating flexibility of the process is increased.

Process for separating low molecular weight compounds from

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Bietigheim-Bissingen, Germany

Eberhard Uhland