TiCl4/XROH/MgCl2/Et3Al催化剂合成宽分子量分布乙烯/1-己烯共聚物

采用MgCl₂负载TiCl₄及1,3-二氯-2-丙醇给电子体(XROH)，与三乙基铝助催化剂组成的催化剂体系，合成了1-己烯共聚率高且宽分子量分布的乙烯/1-己烯共聚物。 讨论了催化体系的组成、配比和聚合条件对乙烯/1-己烯共聚合行为，共聚物结构、分子量及分子量分布的影响。 结果表明，n(Ti)∶n(Mg)=10∶1,n(XROH)∶n(MgCl₂)=2.6∶1,n(Al)∶n(Ti)=100∶1,乙烯压力0.45 MPa,聚合温度80 ℃,聚合时间2 h,共聚单体(1-hexene)浓度0.25 mol/L时,催化效率达23.2 kg/g cat。 采用¹³C NMR、X-ray、SEM、WAXD、DSC、GPC等测试技术对催化剂、共聚物的结构进行了表征。 结果表明，在Zieglar-Natta(Z-N)催化体系中，给电子体多卤代醇与TiCl4结合，载体MgCl2的晶体结构发生了变化。 结晶度降低，有利于催化剂负载量的提高(ω(Ti)=4.8%)和催化效率增大。 催化体系产生了多种活性中心，使聚烯烃分子量分布变宽(15~20)。 多卤代醇还可增强1-己烯与乙烯的共聚能力，在共聚物中1-己烯的摩尔分数达5.1%。

Ethylene/1-Hexene Copolymer with Broadened Molecular Mass Distribution Obtained by Catalysis of TiCl4/XROH/MgCl2/Et3Al

The synthesis of copolymer with high comonomer incorporation and broadened molecular mass distribution from ethylene with 1-hexene catalyzed by co-catalyst TiCl₄/XROH/MgCl₂ and Et₃Al is described. The influences of the catalyst system composition and the polymerization conditions on the behavior of ethylene/1-hexene copolymerization, the structure, molecular mass and molecular mass distribution(MMD) of the obtained copolymer have been discussed in detail. When the copolymerization was performed under the optimum conditions:n(Ti)∶n(Mg)=10∶1, n(XROH)∶n(MgCl₂)=2.6∶1, n(Al)∶n(Ti)=100∶1, P=0.45 MPa, t=80 ℃, Time=2 h and the comonomer concentration in feed=0.25 mol/L, the catalytic activity reached 23.2 kg/g cat. The catalyst particle shape and the structure and properties of the ethylene/1-octene copolymer are characterized with ¹³C NMR, X-ray, SEM, WAXD, DSC and GPC. These results show that the catalytic activity, molecular mass distribution and higher 1-hexene incorporation were considerably improved when the multi-halogen alcohol(XROH) was added into the catalyst system. By adding XROH in the catalyst system made Ti mass fraction of the catalyst increased up to 4.8%; the molar ratio of MMD of the copolymer became broader, ranging from 15 to 20; 1-hexene incorporation within the copolymer chain was higher, up to 5.1%.