PROCESS FOR CONTROLLING THE RELATIVE ACTIVITY OF ACTIVE CENTERS OF CATALYST SYSTEMS COMPRISING AT LEAST ONE LATE TRANSITION METAL CATALYST COMPONENT AND AT LEAST ONE ZIEGLER CATALYST COMPONENT

摘要

A method of controlling the polymer composition of an ethylene copolymer in a process for preparing ethylene copolymers by copolymerizing ethylene and at least one other olefin in the presence of a polymerization catalyst system comprising - at least one late transition metal catalyst component (A) having a tridentate ligand which bears at least two ortho, ortho'-disubstituted aryl radicals, - at least one Ziegler catalyst component (B), and - at least one activating compound (C) by varying the polymerization temperature, a process for copolymerizing ethylene and at least one other olefin in the presence of such a polymerization catalyst system comprising utilizing the controlling method, a method for altering the polymer composition of an ethylene copolymer obtained by copolymerizing ethylene and at least one other olefin in the presence of such a polymerization catalyst system by varying the polymerization temperature and a method for transitioning from one ethylene copolymer grade to another by using the method for altering the polymer composition.