后过渡金属铁系催化剂与Et[Ind]_2ZrCl_2复配催化乙烯原位共聚中的“共单体效应”

研究了以{2-2-MeC6H4N=C(Me)]2C5H3N}FeCl2为齐聚催化剂、以EtInd]2ZrCl2为共聚催化剂复配,在甲基铝氧烷作用下催化乙烯原位共聚的“共单体效应”。在n(Al)/n(Zr)、n(Al)/n(Fe)和n(Al)/n(Fe+Zr)分别为2000时,改变齐聚催化剂/共聚催化剂的配比,均观察到共单体效应。探讨了助催化剂用量、主催化剂用量和聚合温度对共单体效应的影响。助催化剂用量的增加使出现最佳活性点的n(Fe)/n(Zr)发生了前移,而主催化剂用量的增加使出现最佳活性点的n(Fe)/n(Zr)发生了后移。聚合温度的改变使共单体效应的变化规律发生了改变。

Comonomer Effect of the in- Situ Copolymerization of Ethylene Catalyzed by { 2 - [ 2 - MeC6H4N = C(Me)]2C5H3N}FeCl2/Et(Ind) 2ZrCl2 Activated with Methylaluminoxane

Linear low density polyethylene from ethylene as only monomer was prepared by the combined catalyst system of Et ( Ind)2ZrCl2 and {2 - 2 - MeC6H4N = C (Me)]2C5H3N } FeCl2 activated with methylaluminoxane( MAO). Details of the comonomer effect based on combinations of two kinds of single site catalysts were discussed. Comonomer effects were observed in all three cases: n (Al) /n (Zr) = 2000, n (Al) / n(Fe)=2000 and n(Al)/w(Fe+ Zr) =2000. High activity of 7.2 × 106 g/(mol·h) ,5.6 × 106 g/(mol·h) and 6.2× 106 g/(mol·h) respectively appeared as compared with activity of 2.0 × 106 g/(mol·h) of ethylene homo - polymerization under the same conditions. Optimum mole ratio of Fe / Zr increased as co - catalyst decreased or catalysts increased. Values of n (Fe)/n (Zr) also varied with temperatures. Crystallinity and melting temperature of product lowered with incorporation of a - olefins. However, they decreased slowly with the increment of α-olefin when values of n(Fe)/n(Zr) were above 0.5.