Study On The High Molecular Weight Polyethylene For Battery Separator And Highly Active Ziegler-Natta Catalysts

At present,there are few research on polyethylene special material for battery separator.In this work,a new type of ethoxylic magnesium supports and modified magnesium chloride supports are prepared.And Ziegler-Natta catalysts were prepared by supports.In this experiment,citric acid and ammonium ferric citrate were used to improve the comprehensive properties of the supports and catalysts.The structure of the ethoxyl magnesium carriers prepared in the traditional way is relatively loose and easy to produce more fine powder.Besides,the particle size is difficult to regulate and the particle morphology is poor.We used ?-hydroxyl acid to improve the performance of it.The particle size distribution of the carrier is relatively narrow,and there is no fine powder peak and hybrid peak.The average particle size of the carrier d(0.5)=25.51?m,and the particle size distribution index is 1.51.By adding a proper amount of MgCl2,the particle size of the carrier is adjusted in the interval of 59-25 ?m.The surface layer of carrier particles is closely packed and the specific surface area is large,which is favorable for TiCl4 reaction.Polymerization conditions:H2/Ethylene=0.1 MPa:0.7 MPa,Al/Ti= 100/1,polymerization temperature:80?,the activity of ethoxy magnesium catalysts can reach 18416 g PE/g Cat,bulk density:0.33 g/cm3.At present,most of the applications of polyolefin are MgCl2 supported catalysts.We used ED1 to improve the performance of catalysts.The addition of ED1 makes the polymerization activity of the catalysts up from 73 g PE/g cat to 121 g PE/g cat,and the flow index tan?decreases from 0.69 to 0.61,and the content of titanium is increased to 5.36%.Polymerization conditions:H2/Ethylene=0.1 MPa:0.7 MPa,Al/Ti=100/1,polymerization temperature:80?,the activity of the catalyst can reach 53810 g PE/g Cat,bulk density:0.35 g/cm3.The polymers were characterized by SEM,FT-IR,DSC,GPC and particle size analysis.The results showed that the polyethylene particles were in good shape,both mechanical properties and processing properties were taken into consideration.And the properties of the polyethylene meet the requirements of the battery diaphragm.