Michimasa Shimizu

Supported catalyst for olefin polymerization. The role of the third component

Abstract Polymerization of propylene was carried out using a magnesium supported titanium catalyst in combination with triethylaluminium(TEA) and a p-substituted benzoate or a phenylcarbinol as the third component in n-heptane under atmospheric pressure. p-Substituted benzoates produced excellent improvement in isotacticity (95–98%) and there was a linear relationship between isotacticity and Hammetts σ value for the p-substituents. On the other hand, phenylcarbinols (which react with TEA to form hemialkoxides) also increased isotacticity. It is considered that the complexes of TEA with the benzoates are the components which give very high isotacticity ( ≧ 95% ) rather than the reduction products of the benzoates with TEA and that the dissociation of the hemialkoxides is essential for isotacticity, as observed in the case of the phenylcarbinols.