| abstract |
Novel catalysts and processes are disclosed for producing highly crystalline polypropylene and highly crystalline copolymers of propylene with ethylene or propylene with other alpha-olefins. Such catalysts can reduce the amount of low-molecular-weight and, particularly, amorphous polymers formed without serious effect on the polymerization yield. These novel catalysts and processes involve improving an alkylaluminum compound-titanium chloride catalyst by using in combination small amounts of hydrogen sulfide and a sterically hindered, lower alkyl substituted, cyclic, tertiary amine, a sterically hindered, lower alkyl substituted, cyclic, amine oxide, or a trihydrocarbylphosphite. Such catalyst systems are useful in slurry polymerization, bulk polymerization and techniques in which polymerization is accomplished utilizing monomer substantially in the vapor phase. |