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反应法制备的丙烯聚合催化剂上残留的OR基不利于丙烯的定向聚合,OR基不仅有损于载体及催化剂的规整性,也可能妨碍给电子体对某些无规活性位的堵塞作用。催化剂中烷氧基含量与醇分子的大小、解醇方式等有较大关系,选用2-乙基己醇并在解醇及聚合体系中同时添加适量的酯可以显著减少催化剂中烷氧基的残留量,大为改善其定向性。通过IR、X-光粉末衍射及ESR实验,我们认为解醇过程中添加的酯主要是改善MgCl_2微晶的规整性,而聚合体系中添加的酯主要是起着堵塞催化剂上那些空间位阻小、定向性差的Cl~-的作用。
The OR groups remaining on the propylene polymerization catalyst prepared by the reaction method are not conducive to the directional polymerization of propylene. The OR groups not only impair the regularity of the support and the catalyst, but also prevent the blocking effect of the electron donor on some random active sites. Alkoxy content in the catalyst has a great relationship with the size of the alcohol molecule and the alcohol solution method. The use of 2-ethylhexanol and the simultaneous addition of an appropriate amount of ester to the alcohol and polymerization system can significantly reduce the alkoxy Residues, greatly improve their orientation. By IR, X-ray powder diffraction and ESR experiments, we believe that the ester added during the alcoholysis process is mainly to improve the regularity of MgCl 2 microcrystals. However, the added esters in the polymerization system mainly play the role of blocking the steric hindrance of those catalysts , The orientation of the poor Cl ~ - role.