Method for preparing polyolefin plastomer

The invention provides a method for preparing a polyolefin plastomer. The preparation method comprises the following steps: in the presence of an oligomerization catalyst and an oligomerization promoter, ethylene oligomerization is carried out to prepare alpha-olefin; adding a copolymerization catalyst and a copolymerization promoter into the reaction system, and copolymerizing the alpha-olefin to generate a polyolefin plastomer; wherein the oligomerization catalyst is a phosphine nitrogen ligand-chromium salt complex. The copolymer prepared by using the catalyst composition is a polyolefin plastomer of which the alpha-olefin insertion rate is greater than 13wt%, and the copolymer is high in molecular weight and excellent in mechanical property. 本发明提供了一种制备聚烯烃塑性体的方法。所述制备方法包含如下步骤：在齐聚催化剂和齐聚助催化剂的存在下乙烯齐聚制得α-烯烃；向反应体系中加入共聚催化剂和共聚助催化剂，α-烯烃共聚生成聚烯烃塑性体；其中，所述的齐聚催化剂为膦氮配体-铬盐配合物。使用所述催化剂组合制备的共聚物为α-烯烃插入率＞13wt％的聚烯烃塑性体，共聚物分子量高，力学性能优异。