碳桥限制构型催化剂催化乙烯1-己烯共聚和共聚物结构表征

Synthesis and Characterization of Copolymer of Ethylene and 1-Hexene by Carbon Bridge CpCN-CGC

为了碳桥限制构型催化剂(CpCN-CGC)的工业应用,为模试提供工艺参数,我们考察了用这种催化剂,以正庚烷为溶剂,甲基铝氧烷(MAO)为助催化剂的乙烯与1-己烯共聚,考察因素包括聚合温度、乙烯压力、铝锆比、氢气压力和1-己烯浓度.研究发现聚合温度从100升高到140℃,共聚活性先升高再降低,聚合物分子量持续降低;氢气分压从0.1增加到0.8 MPa,共聚活性仍呈先升高再降低,聚合物分子量持续降低的趋势;乙烯压力从0.4升高到1.8 MPa,共聚活性先升高再降低,但聚合物分子量逐步增大;Al/Zr从500升高到1 000,共聚活性逐步增大,但聚合物分子量趋向减小.优化工艺条件为:催化剂用量为10μmol,Al/Zr=700,聚合温度为110~120℃,乙烯压力为1.2~1.4 MPa,1-己烯加入量为20 mL,聚合时间为30 min.此时共聚活性最高达到106g/(mol-Zr·h),共聚物中1-己烯插入率达到了8.34%;用13C-NMR、GPC、DSC表征了聚合产物,计算了二单元组和三段组序列分布,并发现有交替共聚片段HEHE存在.最后还讨论了在聚合物中发现的多种支链的形成机理.

In order to provide technical parameters for industrial model test, methylaluminoxane （MAO） is used as co-catalyst, ethylene/1-hexene copolymerization reaction is carried out catalyzed by CpCN-CGC in n-heptane. The effects of temperature, ethylene pressure, ratio of aluminum to zirconium, hydrogen pressure, and the concentration of 1-hexene on the catalytic behavir and polymer＇s properties are also studied. It is found that the catalytic activity increase first and then reduce as the temperature increase from 100 to 140℃, but the molecular weight of polymer decrease continuously. When the pressure of hydrogen increased from 0.1 to 0.8 MPa, the similar situations happen again. When the pressure of ethylene increase from 0.4 to 1.8 MPa, the catalytic activity increase first and then reduced but the molecular weight of polymer increase contuinually. However, when the ratio of Al/Zr augmented from 500 times to 1 000 times, the catalytic activity increase contuinually but the molecular weight of polymer tends to decrease in general. The optimum technological conditions are obtained：catalyst dosage is 10 μmol, the ratio of Al/Zr=700, polymerization temperature is 110~120℃, the pressure of ethylene is 1.2~1.4 MPa, the dosage of 1-hexene is 20 mL, and the polymerization time is 30 min, as a result, the catalytic activity reaches up to 106g/（mol-Zr·h） and the insertion of 1-hexene in copolymer reaches up to 8.34%. The copolymer is characterized by 13C NMR, DSC and GPC, and the dyad and triad distribution and number-average sequence length of these copolymers are quantitatively determined, and found that there are many types branch chain in polymer and the mechanism was offered, however, it is also found there are alternating copolymer HEHE fragment exists in copolymer.