Process for producing polyolefin granules having an average particle size greater than 600 microns

摘要

Polyolefin granules having an average particle size diameter greater than 600 microns, preferably about 1000 microns or greater are obtained by polymerizing monoolefins in the presence of a titanium catalyst having an average particle size diameter of greater than about 35 microns and preferably 40 to 65 microns. The titanium catalysts are obtained by reducing titanium tetrahalide in the presence of a suitable organometallic reducing compound such as diethylaluminum chloride under controlled conditions of temperature, reduction rate and concentrations to obtain a titanium halide reduced solids product seeds having an average particle size diameter of about 20 microns or greater and thereafter simultaneously and without interruption adding to the seeds containing system titanium tetrahalide and organometallic reducing compound such as diethylaluminum halide at a rate such that the reduction of titanium tetrahalide to titanium trihalide is about 6x10-4 to about 0.02 millimoles per liter per second per m2 of available preformed titanium trihalide surface area until solids product of desired size are obtained.