Studies on the polymerization of ethylene using a high‐yield MgCl₂‐supported titanium catalyst, 1. Effects of synthesis parameters on catalyst activity and polymer properties

The preparation of a highly active Ti‐Mg catalyst in two steps is reported. the first step is a Grignard reaction conducted in hexane with an under‐stoichiometric amount of tetrahydrofuran. In the second step the Grignard suspension is treated with a TiCl 4 /CCl 4 mixture. Owing to optimized synthesis conditions after a thermal activation the catalyst suspension is ready for use in combination with an alkylaluminium cocatalyst without further separation and drying operations. Because of its high response to H 2 the catalyst may preferably be used for the production of polyethylene (PE) for injection moulding. Depending on the Ti content the catalyst shows an activity of between 184 and 250 kg PE per g Ti per h and per bar for a PE with melt flow index between 20 and 30 g/10 min. The content of Ti 4+ in the catalyst is high (up to 72 wt.‐%). The catalyst suspension shows a marked resistance against reduction by the cocatalyst. The catalytic activity not only depends on the mole ratio of the individual catalyst components but even more on their actual concentration in the reaction medium.