亚胺基吡啶钴催化乙烯齐聚合和原位共聚合

Ethylene oligomerization and copolymerization with cobalt-based catalysts bearing 2,6-bis(imino) pyridyl ligand/MAO

研究了{2-[2-Me-4-OMe-C_6H_3N=C(Me)]_2C_5H_3N}CoCl_2(催化剂1)催化乙烯齐聚合以及它与不同茂金属催化剂Et[Ind]_2ZrCl_2(催化剂2)、Me_2Si[Ind]_2ZrCl_2(催化剂3)和Me_2Si[2-Me-Ind]_2ZrCl_2(催化剂4)复配,以甲基铝氧烷(MAO)为助催化剂催化乙烯原位共聚合。讨论了茂金属催化剂类型和聚合温度的改变使共聚活性发生变化的规律,并对部分产物的性能进行了测试。结果表明：催化剂1与催化剂2复配在40,60,80℃时催化乙烯原位共聚合均出现了正共单体效应,60℃时出现共单体效应的最大活性为6.4 Mg/(mol·h),高于40℃和80℃时的相应值。同时,催化剂1/催化剂2/MAO和催化剂1/催化剂3/MAO体系随着共聚催化剂金属活性中心的夹角减小,出现正共单体效应时最佳配比点的活性下降；而催化剂1/催化剂4/MAO体系出现了负的共单体效应,密度最低可达到0.9209g/ cm^3.所得支化聚乙烯的物理性能取决于α-烯烃的插入率,插入率主要与茂金属催化剂的结构有关。

This paper studied ethylene oligomerization catalyzed by {2-[2-Me-4-OMe-C6H3N = C(Me)]2C5H3N} CoCl2 (catalyst I) and ethylene in-situ copolymerization catalyzed by a compound system consisting of catalyst I, metallocene catalyst Et[Ind]2ZrCl2 (catalyst II), Me2Si[Ind]2ZrCl2, (catalyst III) and Me2Si[2-Me-Ind]2ZrCl2 (catalyst IV) in the presence of methylaluminoxane (MAO) as co-catalyst. The rule of variation in copolymerization activity with type of metallocene catalyst and polymerization temperature was discussed and furthermore, the performance of some resultant polymers was determined. The experimental data show that in case of compounding catalyst I and catalyst II to catalyze the ethylene in-situ copolymerization at temperature of 40°C, 60°C and 80°C respectively, a positive comonomer effect occurs; the maximum activity when comonomer effect appeared at 60°C reaches 6.4 Mg (/mol) · h, that is higher than the corresponding value at 40°C and 80°C. At the same time, as the angle between metal active sites on the copolymerization catalyst become smaller, both compounding systems of catalyst I/catalyst II/MAO and catalyst I/catalyst III/MAO have a lowered activity at their optimum proportion when the positive comonomer effect occurred. On the other hand, negative comonomer effect appears when using compounding system of catalyst I/catalyst IV/MAO; the density of the resultant copolymer can attain its lowest value of 0.9209 g/cm3. The physical properties of the branched polyethylene so prepared depend on the insertion ratio of α-olefin that is mainly relevant to the structure of the metallocene catalyst.