C - Chemistry – Metallurgy – 08 – F
Patent
C - Chemistry, Metallurgy
08
F
400/2042
C08F 297/04 (2006.01)
Patent
CA 1180840
Abstract of the disclosure: 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 mono- lithium-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 to 40°C, is kept at from 45 to 70°C, with use of reflux cooling. After all the monomer feed has been added the reaction temperature is lowered to 30- 40°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 the total amount of monovinyl-aromatic monomer can be added, the sum of the amounts of monovinyl- aromatic monomer added in the first and second process stages being at most 90 % by weight of the total amount of monovinyl-aromatic monomer. The monovinyl-aromatic monomer added in the second process stage is polymerized to virtually complete conversion, employing the tempera- ture profile described for stage (a). In process stage (c), the remainder of the monovinyl-aromatic monomer and all of the conjugated diene are added, at least predominantly in the form of a mixture, and poly- merized so that the reaction temperature does not rise above 90 - 110°C. Finally, after virtually complete conversion of the monomers, and preferably without prior cooling, a suitable liquid polyfunctional coupling agent is run in undiluted and the mixture of the linear block copolymers obtained, which still contain active terminal lithium-carbon bonds, is coupled, with stirring, to form branched block copolymers. The products prepared according to the invention are used for injection molding.
383818
Dorn Ingo H.
Gausepohl Hermann
Gerberding Karl
Heinz Gerhard
Jung Rudolf H.
Basf Aktiengesellschaft
Robic Robic & Associes/associates
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