PE-UHMW聚合用氧基硅烷内给电子体Ziegler-Natta催化剂的制备及应用

Preparation and Application of Ziegler-Natta Catalyst with Internal Electron Donors of Oxosilane for PE-UHMW Polymerization

采用实验室自制的两种复合型氧基硅烷内给电子体:二甲基二(2-酚基乙氧基)硅烷(IED1)和二甲基二(2-氯乙氧基)硅烷(IED2),将两种内给电子体配置Ziegler-Natta催化剂并进行乙烯的催化聚合以制备超高分子量聚乙烯(PE-UHMW)。考察了两种内给电子体加入对Ziegler-Natta催化剂的载钛量、催化剂活性、催化剂的微观形貌及聚合物分子量等因素的影响,并考察催化剂加入量、聚合温度、聚合时间、助催化剂加入量对PE-UHMW聚合效果的影响。由于IED1结构中含有4个含氧基团,电子云密度高于IED2,因此IED1对催化剂活性以及聚合物分子量影响较大。最终确定PE-UHMW聚合工艺条件为:以IED1为内给电子体,催化剂加入量为12 mg/L,IED1与载体氯化镁的物质的量之比为1∶4,聚合温度为75℃,聚合时间为2 h,催化剂中Al/Ti物质的量之比为80。在此工艺条件下催化剂的催化效率为17.1 kg/(g·h),催化剂载钛量为5.8%,PE-UHMW堆密度为0.3 g/cm^(3),PE-UHMW分子量为4.0×10^(6)。

Two types of composite oxygenosilane internal electron donors were made in the laboratory:dimethyl bis(2-phenolethoxy)silane(IED1)and dimethyl bis(2-chloroethoxy)silane(IED2).Two internal electron donors were configured with Ziegler-Natta catalysts and performed catalytic polymerization of ethylene for preparing ultra-high molecular weight polyethylene(PEUHMW).The effects of the addition of two internal electron donors on the titanium loading,catalyst activity,and micro morphology of the Ziegler-Natta catalyst and polymer molecular weight were investigated.The effects of catalyst addition,polymerization temperature,polymerization time,and assistant catalyst addition on the polymerization efficiency of PE-UHMW were also investigated.Since the structure of IED1 contains four oxygen-containing groups,the density of electron cloud is higher than that of IED2,so IED1 has a greater impact on catalyst activity and polymer molecular weight.The final determined process conditions are:IED1 is used as the internal electron donor,the catalyst addition is 12 mg/L,the molar ratio of IED1 and MgCl_(2)as carrier is 1∶4,the polymerization temperature is 75℃,the aggregation time is 2 h,molar ratio of Al/Ti in catalyst is 80.Under this process condition,the catalytic efficiency of the catalyst is 17.1 kg/(g·h),the titanium loading capacity of the catalyst is 5.8 wt%,the stack density of PE-UHMW is 0.3 g/cm3,the molecular weight of PE-UHMW is 4.0×10^(6).