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 POLYETHYLENEOF ULTRA-HIGH MOLECULAR WEIGHT

摘要

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