Research On The Reaction System For The Preparation Of Polybutadiene With High CIS-1,4Configuration

It is well known that high cis-1,4-polybutadiene could be synthesized via coordination polymerization of butadiene (Bd) with Ni(naph)2-Al(i-Bu)3-BF3-OEt2catalyst system, in which BF3-OEt2could not dissolve well in hexane. In order to improve the Ni-based catalyst, in this paper, P and H were introduced as the ligands of BF3into the polymerization of butadiene.In Ni(naph)2-Al(i-Bu)3-BF3·(P+H) system, the effect of the molar ratio of P and H, the concentration of BF3, polymerization temperature, monomer concentration, the dosage of catalyst and catalyst components ratio on monomer conversion, microstructure of polybutadiene, intrinsic viscosity, weight-average molecular weight and its distribution were investigated respectively. The results were shown as follows:<1> BF3·(P+H) could dissolve well in hexane, and its stability and solubility could be increased greatly. The concentration of BF3could reach4.4×10-5mol/mL. The cis-1,4unit content of polybutadiene could reach 99.0%, and gel content of polybudiene could be decreased below0.3%and even to no gel.<2> The solubility of BF3, the conversion of butadiene could be decreased, while the cis-1,4%of polybutadiene was increased a little, When increase the molar ratio of P/H.<3> the conversion of butadiene could be improved with increasing the concentration of butadiene and polymerization temperature, the molar ratio of B/Nj,Al/Ni and Ni/Bd.<4> The weight-Average molecular weight of polybutadiene could be increased from5×105g/mol to1.14×106g/mol by reducing B/Ni molar ratio from10to2. When P was introduced into the new system as the fourth component and the molar ratio of P/Ni(naph)2reached100, the butadiene conversion and the cis-1,4unit content of PB could reach85%and97.5%respectively.<5> The civ-1,4unit content of polybutadiene could be increased with increasing the content of Al, decreasing the molar ratio of B/Ni and polymerization temperature.<6> The optimum catalyst system and polymerization conditions were:[Bd]=8g/100mL～13g/100mL, P/H=0.5～3.0,[BF3]=2×10-5mol/L～4×10-5mol/L, B/Ni=5～8, Al/Ni=6～10, Ni/Bd＝0.5×1O-4～1.0×10-4。<7> The experimental results in the5L reactor was coincident with the above, which indicating that the butadiene conversion could reach60%while the cis-1,4unit content of PB was more than97.8%when the molar ratio of B/Ni was6.<8> When the catalyst system was Ni/Bd=1.0×10-4, Al/Ni=6, B/Ni=6, the Tensile strength and Elongation at break of polybutadiene could reach20MPa and511%respectively. The Mechanical properties is superior than that of BR9000.