Propene polymerization with MgCl 2 ‐supported TiCl 4 /dioctylphthalate catalyst. I. Catalyst behavior

Slurry polymerization of propene using MgCl 2 ‐supported TiCl 4 /dioctylphthalate catalysts were carried out in a semibatch reactor at a constant pressure to examine the effects of polymerization conditions on catalyst activity and polymer isotacticity. The catalysts were prepared at 80, 90, and 105°C, which gave different compositions of chemical complexes associated with the diester. Five alkyl aluminums (triethyl, triisobutyl, tri‐ n ‐hexyl, tri‐ n ‐octyl, and isoprenyl) were studied as cocatalysts. Among these, triethyl aluminum was found to be most effective for the catalysts prepared at 80 and 95°C, and tri‐ n ‐hexyl aluminum for the catalyst prepared at 105°C. Dimethoxydiphenyl silane and 2,2,6,6‐tetramethylpiperidine were employed to study their effects as an external Lewis base for the catalyst prepared at 105°C. In both cases, a small amount of either base resulted in significant increase in activity and isotacticity, which can be attributed to the high level of phthaloyl chloride complex in the catalyst. © 1995 John Wiley & Sons, Inc.