PROCESS FOR PREPARING A ZIEGLER-TYPE SPHERICAL CATALYST FOR ALPHA-OLEFIN POLYMERIZATION, SPHERICAL CATALYST, PROCESS FOR PREPARING A SPHERICAL POLYETHYLENE OF ULTRA-HIGH MOLECULARWEIGHT AND SPHERICAL POLYETHYLENE OF ULTRA-HIGH MOLECULAR WEIGHT

摘要

A process for preparing a spherical support for thepolymerization of alpha-olefins from an ammonium dawsonitewhich is spray-dried and formed into spherical particles whichare then calcined and impregnated with titanium to produce aspherical catalyst of good mechanical strength is described.Also described is the polymerization process which, in thepresence of the spherical catalyst, yields polyolefinparticles which preserve the spherical characteristics of thesupport, with low flow angle and good bulk density, as well asthe product polyethylene obtained from the process.