Patent ID: 8388216

Claim:
A method for the devolatilization of polymer melts comprising the following steps: providing a processing installation ( 1 ; 1 a ; 1 b ) comprising a first extruder ( 2 ) which comprises several rotatably drivable first shafts ( 15 , 16 ) which are provided with first treatment members ( 20 , 21 ); and several first devolatilization zones ( 24 , 25 ) with first devolatilization ports ( 26 , 27 ); a second extruder ( 4 ) arranged downstream of the first extruder ( 2 ) in a direction of conveyance ( 3 ) which comprises several rotatably drivable second shafts ( 40 , 41 ) which are provided with second treatment members ( 42 , 43 ), with the external diameter (d a ) of the first treatment members ( 20 , 21 ) being no more than equal to the external diameter (D a ) of the second treatment members ( 42 , 43 ); and several second devolatilization zones ( 58 , 59 , 60 ) with second devolatilization ports ( 61 , 62 , 63 ); a transfer zone ( 50 ) which interconnects the extruders ( 2 , 4 ); a devolatilization unit ( 48 ) which is arranged in the transfer zone ( 50 ); and an adjustable throttle ( 51 ) which is upstream of the devolatilization unit ( 48 ) in the direction of conveyance ( 3 ) and arranged in the transfer zone ( 50 ); supplying a polymer melt to the first extruder ( 2 ), with the first extruder ( 2 ) being operated at a first speed (n 1 ) of the first shafts ( 15 , 16 ) in such a way that volatile components escape from the polymer melt via the first devolatilization ports ( 26 , 27 ) so that the polymer melt becomes more viscous; adjusting the energy input into the polymer melt in the first extruder ( 2 ) using the throttle ( 51 ); supplying the more viscous polymer melt under pressure to the devolatilization unit ( 48 ) which comprises a perforated plate ( 54 ) and a clearance ( 55 ) arranged downstream in the direction of conveyance ( 3 ) so that the polymer melt has a larger surface area in the no more than partially filled clearance ( 55 ) after passing through the perforated plate ( 54 ) and other volatile components escape from the polymer melt; and supplying the polymer melt being discharged from the devolatilization unit ( 48 ) to the second extruder ( 4 ), with the second extruder ( 4 ) being operated at a second speed (n 2 ) of the second shafts ( 40 , 41 ), which is lower than the first speed (n 1 ), in such a way that other volatile components escape from the polymer melt via the second devolatilization ports ( 61 , 62 , 63 ).