Synthesis of MgCl2-supported dichlorobis(4,4,4-trifluoro-1-phenyl-1,3-butanedionato)titanium catalysts with different titanium contents and their application to propene polymerization

Various MgCl2-supported Ti(4,4,4-trifluoro-1-phenyl-1,3-butanedionato)(2)Cl-2 catalysts with different Ti contents (0.017 similar to 0.002 mmol/g) were synthesized and applied to propene polymerization using tri ethylaluminium and di-i-propyldimethoxysilane (DIPDMS) as the cocatalyst and external donor, respectively. When polymerization was conducted in the absence of DIPDMS, neither the activity nor the isospecificity of catalyst were dependent upon the Ti content. However, the effect of DIPDMS on the catalyst performance was found to be markedly dependent upon the Ti content, i.e., the addition of DIPDMS to the catalyst with low Ti content caused a prominent increase in the activity for isotactic polymerization. As a result, the present catalyst with low Ti content gave a highly isotactic polypropene with T-m= 169.3 degrees C and [mmmm] > 99% in high selectivity (I.I.. = 97.7%).