Extruder having extruder screw with multiple degassing zones and diameters for the viscosity-increasing processing of meltable polymers

An extruder for viscosity-increasing processing of meltable polymers, the extruder comprising:

• an extruder screw with helical extruder screw flights, an outer diameter of the extruder screw being subdivided into a diameter start region, a diameter center region and a diameter end region, the diameter center region having a larger outer diameter than at least one of the diameter start region or the diameter end region;
• and
• a housing with an inner housing bore, in which the extruder screw is rotatably arranged,
• wherein the extruder screw includes a first transition cone formed between the diameter start region and the diameter center region and a second transition cone formed between the diameter center region and the diameter end region,
• wherein at least two degassing zones are formed in the diameter center region of the extruder screw, each of the at least two degassing zones having at least one suction opening that extends from the inner housing bore to an outer side of the housing,
• wherein a plurality of rotationally driven satellite screws surround the extruder screw in a region of a first degassing zone of the at least two degassing zones, the satellite screws each rotate individually about a satellite axis and rotate together with the extruder screw,
• wherein a second degassing zone of the at least two degassing zones is formed upstream of the first degassing zone, and
• wherein a depth of screw channels formed between the extruder screw flights is greater in both of the first and second degassing zones than in at least one sealing and compression section that is formed between the first and second degassing zones.