ORGANOMETALLICS IN ETHYLENE POLYMERIZATION WITH A CATALYST SYSTEM TICL4-AL(C2H5)2CL-MG(C6H5)2 .2. POLYMERIZATION PROCESS IN PSEUDO-SOLUTION

A study has been made of ethylene polymerization in pseudo-solution with a catalyst system TiCl4/Al(C2H5)2Cl/Mg(C6H5)2 in the presence of hydrogen as a regulator of polyethylene molecular weight. The polymerization process in pseudo-solution by adjustment of hydrogen makes it possible to produce polyethylene having a wide range of molecular weights. For this purpose melt indices between 0°-50°C/min are desirable and these values are not reached with a suspension type of ethylene polymerization with a catalyst system TiCl4/Al(C2H5)2Cl/Mg(C6H5)2. The effect of the molar ratio cocatalyst/catalyst (Al/Ti and Mg/Ti) on the catalyst activity and on the polyethylene molecular weight was studied, together with the content of hydrogen as a regulator of the molecular weight. The catalyst productivity increased to some limiting molar ratio Mg/Ti and Al/Ti and further increase of organometallics in the catalyst system did not influence the polymer molecular weight. In the case of ethylene polymerization with this catalyst combination in the presence of hydrogen, some activation of the catalyst was observed. Two mechanisms, which may account for the activation effect of the hydrogen are discussed. © 1978.