| 摘要 |
<p>Catalysts for the polymerization of alpha-olefins, comprising the product of the reaction between: (a) a metalorganic Al compound; (b) an electron-donor compound reactive towards MgCl2 but which results not to be completely complexed with Al-triethyl at the equivalent point of the potentiometric titration under standard conditions; (c) a solid comprising a halogenated Ti compound supported on an anhydrous Mg halide and at least one of the following activators: (1) an Al, Fe, Mn, Sb or Zn compound containing at least one metal-halogen bond; (2) a complex between an electron-donor compound and a Lewis acid chosen among the halides of the metals of Groups II-VIII of the Periodic System other than Ti; (3) a compound or composition, inert towards the Mg halide, having a dielectric constant at 20 DEG C. higher than 2; compounds (1), (2) and (3) being extractable from the solid for at least 30% by mols by treatment with toluene at 80 DEG C. for 2 hours, and the surface area of the solid after extraction being higher than 20 m2/g.</p> |
