Patent ID: 6479609
Filing Date: 2002-11-12
Classification: C08F,C08L,Y10S

Abstract:
A broad MWD polyethylene having the following characteristics:i) intrinsic viscosity (I.V.) ranging from 0.5 to 6 dl/g; ii) molecular weight distribution Mw/Mn>8; and iii) cold xylene solubility XS<1.2% wt., said polyethylene being obtained from a multi-stage process for the polymerization of ethylene, and optionally one or more a-olefins comprising from 3 to 10 carbon atoms, for producing a polymer having broad MWD, said process comprising the following stages: (A) polymerizing ethylene, and optionally an &agr;-olefin, in one or more reactors, in the presence of a catalyst comprising the reaction product between: (i) a solid component comprising a compound of a transition metal MI selected from Ti and V, not containing MI-&pgr; bonds, and a halide of Mg in active form, optionally further comprising an electron-donor compound (internal donor); (ii) an alkyl-Al compound and optionally an electron-donor compound (external donor); (B) contacting the product obtained in stage (A), in any order whatever, with: (a) compound capable of deactivating the catalyst of stage (A); (b) a zirconocene compound of formula (I): wherein R1, R2, R3 and R4, the same or different from each other, are selected from the group consisting of hydrogen, linear or branched, saturated or unsaturated, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C7-C20 alkylaryl and C7-C20 arylalkyl radicals, optionally containing one or more Si or Ge atoms, or wherein two substituents of R1, R2, R3 and R4 form a ring having from 4 to 8 carbon atoms; R5 and R6, the same or different from each other, are selected from the group consisting of linear or branched, saturated or unsaturated C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C7-C20 alkylaryl and C7-C20 arylalkyl radicals, optionally containing one or more Si or Ge atoms, or wherein one pair of vicinal R6 substituents of the same indenyl group forms a ring having from 4 to 8 carbon atoms; m is an integer ranging from 0 to 2; n is an integer ranging from 0 to 4; the groups X, the same or different from each other, are hydrogen, halogen, â€”R, â€”OR, â€”SR, â€”NR2 or â€”PR2, wherein R is selected from the group consisting of linear or branched, saturated or unsaturated, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C7-C20 alkylaryl and C7-C20 arylalkyl radicals, optionally containing one or more Si or Ge atoms; and (c) optionally an activating cocatalyst; (C) polymerizing ethylene, and optionally an &agr;-olefin, in one or more reactors, in the presence of the polymer obtained from stage (B).