| 摘要 |
<p>A Ziegler catalyst system is formed from the combination of an organometallic cpd. of group I, II or III and a heavy metal cpd. of group IV, V or VI, which is carried on a support. This support is a crystalline active complex obtd. by reacting Mg, gaseous HCl and one or more aliphatic, aromatic or alkylaromatic alcohols in the liq. or gaseous state at 60-300 degrees C. The active complex has: (a) a free alcoholic OH gp. content of 1-25, (3-10), wt. %; (b) a chlorine content of 15-70, (30-60) wt. %; (c) a Mg content of 5-35, (10-25)wt. %; (d) a porosity of 0.1-1, (0.3-0.7) cm3/g; and (e) a specific surface of 1-200, (5-100), m2/g. The catalyst system can be used to prepare e.g. polyethylene which is practically linear, with a melt index of 0.1-20, a crystallinity of 50-84%, and a density of 0.95-0.97, the wide melt index range making the products suitable for all types of working, e.g. extrusion, blow-moulding.</p> |
