Dispersion head for extruder

Claim 1

THE COMBINATION WITH AN EXTRUDER OF ORGANIC PLASTIC MATERIAL HAVING A BARREL WITH A PLASTICIZER SCREW AND SHAFT THEREFOR ROTATING THEREIN, OF A DISPERSION HEAD FOR CAUSING MIXING BY SUBJECTING THE PLASTIC MATERIAL ALTERNATELY TO EXTREME SHEARING STRESSES AND SUDDEN RELIEF THEREFROM, SAID DISPERSION HEAD COMPRISING A BARREL EXTENSION AT THE DISCHARGE END OF THE EXTRUDER BARREL, THE EXTENSION HAVING A CYLINDRICAL BORE, AND A SHAFT EXTENSION AT THE END OF THE SCREW SHAFT AND ROTATABLE THEREWITH, THE SHAFT EXTENSION HAVING LONGITUDINALLY SPACED CYLINDRICAL SHEARING SECTIONS THE PERIPHERAL SURFACES OF WHICH HAVE A PROXIMITY TO THE SURFACE OF THE BORE OF A FEW MILS, THE LENGTHWISE EXTENT OF THE CYLINDRICAL SECTIONS BEING A VAST MULTIPLE OF THE CLEARANCE BETWEEN THE CYLINDRICAL SECTIONS AND THE BORE THEREBY PROVIDING A MILLING ACTION CHARACTERIZED BY HIGH SHEARING STRESSES SAID SHAFT EXTENSION HAVING INTERMEDIATE CYLINDRICAL SECTIONS ALTERNATING WITH SAID EXTENDED CYLINDRICAL SHEARING SECTIONS THE SURFACES OF WHICH ARE SPACED FROM THE SURFACE OF THE BORE TO PROVIDE ANNULAR AREAS OF UNIFORM THICKNESS THROUGHOUT THEIR CIRCUMFERENCE AND HAVING A LENGTHWISE EXTENT PROVIDING A SUBSTANTIAL VOLUME FOR MIXING THE PLASTIC MATERIAL, WHEREBY ROTATION OF THE SCREW AND SHAFT EXTENSION SUBJECTS THE PLASTIC MATERIAL LEAVING THE EXTRUDER BARREL ALTERNATELY TO HIGH SHEARING STRESSES BETWEEN THE CYLINDRICAL SURFACES OF THE ROTATING EXTENDED CYLINDRICAL SECTIONS AND THE STATIONARY SURFACE OF THE BORE AND TO MIXING IN SAID AREAS OF SUBSTANTIAL ANNULAR VOLUME.