Preparation of branched block copolymers

US4418180A · kind A · utility

Assignee

• BASF SE

Inventors

• Gerhard Heinz · Bad Dürkheim, DE
• Burghard Schmitt · Worms, DE
• Ingo H. Dorn · Schifferstadt, DE
• Hermann Gausepohl · Mutterstadt, DE
• Karl Gerberding · Monsheim, DE
• Rudolf H. Jung · Worms, DE
• Hans Mittnacht · Weinheim, DE
• Jurgen Pohrt · Mannheim, DE
• Paul Witimer · Landau, DE

Key dates

• Filing date: Aug 27, 1981
• Grant date: Nov 29, 1983
• Expiry date: Aug 27, 2001

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08F297/044
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process for the preparation of branched block copolymers of from 60 to 95% by weight of a monovinyl-aromatic monomer and from 40 to 5% by weight of a conjugated diene by polymerizing the monomers in an inert solvent in the presence of a monolithium-hydrocarbon as the initiator, wherein, in a first process stage (a), from 50 to 80, or where necessary at most 90, % by weight of the total amount of monovinyl-aromatic compound are polymerized to virtually complete conversion in the presence of a relatively small amount of the monolithium-hydrocarbon. This stage is carried out by starting with from 30 to 70% by weight of the vinyl-aromatic monomer and adding from 70 to 30% by weight in the feed, during the polymerization, in such a way that the polymerization temperature, which at the start of the polymerization is from 30.degree. to 40.degree. C., is kept at from 45.degree. to 70.degree. C., with use of reflux cooling. After all the monomer feed has been added, the reaction temperature is lowered to 30.degree.-40.degree. C. by evaporative cooling. In a second process stage (b), an additional amount of initiator is added to the reaction solution, after which from 1 to 30% by weight of…