| 摘要 |
<p>Ziegler-Natta catalyst composition capable of producing ethylene/alpha-olefins copolymers, particularly linear low density polyethylene; the composition having an improved stability of its behaviour during polymerization in respect to time.
The Ziegler-Natta catalyst composition comprises:
A) a procatalyst, which procatalyst comprises
a) an AI compound having the formula Al(alkyl) x Cl 3-x (I), where alkyl is an alkyl group with 1 to 12 and 0 ‰¤ x ‰¤ 3,
b) a magnesium hydrocarbyloxy compound of formula Mg(OR 1 ) 2-n (R 2 ) n (II), wherein each R 1 and R 2 is independently a C 1-20 hydrocarbon residue which may optionally be substituted with halogen and 0 ‰¤ n < 2 and
c) a chlorine-containing titanium compound of the formula ClyTi(OR 3 ) 4-y (III), wherein R 3 is a C 2-20 hydrocarbon residue and y is 1, 2, 3 or 4,
with compounds a), b) and c) being supported on a particulate inorganic carrier and
B) a halogenated aluminium alkyl cocatalyst of the formula (IV) (C 1 -C 3 -alkyl) m -Al-X 3-m , wherein X is chlorine, bromine, iodine or fluorine and m is 1 or 2,
whereby the composition shows a reduced change of comonomer response with polymerization time compared to compositions using non-halogenated cocatalysts.</p> |
