Patent ID: 7380973

Claim:
An Extruder for the reprocessing of a thermoplastic polycondensate, comprising: an inlet opening for introducing the polycondensate to be reprocessed in the solid state, an outlet opening for discharging the reprocessed polycondensate in the melted state, a plurality of closely intermeshing screw shanks, which are arranged in a barrel, extending from the inlet opening in the direction of an outlet opening and having at least a first conveying zone, for conveying the polycondensate in the solid state, a second conveying zone, for conveying the polycondensate in the melted state, and also kneading elements, arranged between the first conveying zone and the second conveying zone, for melting the polycondensate, at least one degassing opening, provided in the barrel in the region of the first conveying zone, and heating means for heating the barrel in the region of the first conveying zone, wherein the barrel is divided into an inner barrel and an outer barrel and the screw shanks are arranged in an annular form between the inner barrel and the outer barrel, the screw shanks separating an outer space, formed between the outer barrel and the screw shanks, from an inner space, formed between the inner barrel and the screw shanks, and wherein, in the region of the first conveying zone, the polycondensate is located either in the inner space and the degassing opening is connected to the outer space, or the polycondensate is located in the outer space and the degassing opening is connected to the inner space, and wherein, in the first conveying zone and in the region of the inlet opening therein, the pitch of each screw shank is reduced in the direction of the outlet opening.