| 主权项 |
1. A devolatilisation apparatus comprising at least one extruder, the extruder comprising:
a barrel and n barrel holes Bn having associated hole diameters Dn where n is an integer, one or more screws Wn arranged concentrically in each of the barrel holes Bn and configured to be rotatable within the barrel holes, wherein each screw has an axis of rotation An and is equipped with treatment elements, the treatment elements having a cross-sectional profile orthogonal to the axis of rotation, wherein the cross-sectional profile in a circumferential direction has:
m relative maxima Rmmax n in respect of a radial dimension of the cross-sectional profile to the axis of rotation An of the screw Wn, where m is an integer from 1 to 8,a maximum value Rmax n in respect of radial dimension of the cross-sectional profile to the axis of rotation An of the screw Wn, where Rmax n fulfils:
Rmax n<=(Dn/2) at least one feed zone, one or more devolatilisation zones comprising in each case at least one devolatilisation opening which is suitable for discharge of volatile constituents from a polymer-containing medium from the extruder, at least one discharge zone, and wherein the treatment elements comprise screw elements having a pitch t, and the screw element are configured so that each of the following three conditions are met:
S1) the cross-sectional profile has at least one relative maximum Rmmax n based on the radial dimension of the profile curve, for which:
0.420 Dn<Rmmax n<0.490 Dn,S2) 1.38 Dn<t<5.00 Dn, andS3) the cross-sectional profile of the respective screw element has no tangential angle β greater than 30°, on the active flanks located at the front in the direction of rotation in the range of the radial dimension from 0.95 Rmax to Rmax, where the tangential angle β is defined as
a smaller of the two angles formed on drawing tangents at any point on the cross-sectional profile of the treatment element at which the cross-sectional profile cannot be continually differentiated, andis 0° at any point on the cross-sectional profile of the treatment element at which the cross-sectional profile can always be differentiated. |
