Patent Number: 6,309,574

Title: Extrusion of high molecular weight polymers

Abstract: A method for manufacturing an extrudable product including the steps of (a)providing an apparatus including an extruder having at least one rotorwith first grooves, at least one stator with second grooves and aclearance between the rotor and the stator, the first grooves, secondgrooves and clearance forming a processing cavity having a volume that isequal to the volumes of the first grooves, the second grooves and theclearance, the processing cavity having a cross-sectional area thatdecreases continuously along at least a part of an axis of the extruder,the extruder further having a supply for feeding a material to be extrudedinto the processing cavity; b) feeding the material to be extruded in apowder, pellet or granuate form into the processing cavity through thesupply and causing rotation of the rotor relative to the stator such thatthe material is forced to proceed along an x-axis in a shear zone of theextruder where the material is subjected to a shear which causes afictional heat that melts a part of the material and forms a bed of mainlyunmelted particles and melt around the particles, the processing cavitybeing completely filled at a cross-sectional portion thereof that is adistance from the end of the extruder, the unmelted particles beingpresent in the cross-sectional portion in an amount sufficient to increasea pressure in the extruder to a level that is higher than that needed forpushing the material further along the x-axis to a die.

Inventors: Jarvenkyla; Jyri (Hollola, FI), Kirjavainen; Kari (Espoo, FI), Sjoberg; Michael (Vaster.ang.s, SE)


International Classification:

Expiration Date: 10/32013