Process for the polymerization of vinyl aromatic monomers, especially styrene, optionally copolymerized with dienes, with improved control

摘要

A process for the homopolymerization of vinyl aromatic monomers or copolymerization of vinyl aromatic monomers and dienes comprises polymerization of the monomers in the presence of at least an organoalkali metal, an organomagnesium compound and an organoaluminum compound. Independent claims are included for: (i) an initiator composition comprising an organoalkali metal, an organomagnesium compound and an organoaluminum compound, whereby the molar ratio of magnesium to the alkali metal is 0.2-3.8 and the molar ratio of aluminum to the alkali metal is 0.2-4; (ii) a process for the preparation of an initiator composition by dissolving the organometallic compounds in inert hydrocarbons and allowing the mixture to mature at 0-120 deg C for at least 5 minutes.