Sam S. Lee

Organotin(IV) oxides and sulfides as modifiers of propene polymerization catalysts

Studies of a number of organotin(IV) oxides and sulfides as modifiers of Ziegler-type propene polymerization catalysts are reported. The general trend observed is that organotin(IV) sulfides provide better catalyst activity-stereospecificity combinations than the corresponding oxides. Among the various modifiers studied, μ-thiobis[tri-butyltin(IV)] was found to exhibit the best overall modifying effect. Combination of an organotin(IV) sulfide with a second modifier of the aromatic amine, N-oxide, phosphite ester or cyclic ether type in a binary modifier package was shown to lead to catalyst systems with excellent stereospecificities and activities ranging from acceptable to outstanding. Possible interactions and reactions of the organotin modifiers with the components of the catalyst system are discussed.