Basf Aktiengesellschaft

Ingo H Dorn

Hermann Gausepohl

Gerhard Heinz

Karl Gerberding

Rudolf H Jung

Klaus Hess

Hans Christoph Horn

Burghard Schmitt

Hans Mittnacht

Roland Spahl

Walter Kastenhuber

Joachim Stedefeder

Wolfgang Linke

Hans-Ingo Joschek

Jurgen Pohrt

Paul Witimer

Gunter Dinkhauser

Horst Kuhn

A process for decomposing organohalogen compounds which are present in dust-laden gases which have a carbon content of less than 0.6% by weight, by oxidative breakdown with the aid of solid catalysts suitable for this purpose, wherein

Decomposition of organohalogen compounds in dust-laden-waste gases

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 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 temperature 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 polymerized so that the reaction temperature does not rise above 90.degree.-110.degree. 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.

Preparation of branched block copolymers

Copolymers of crotonic acid are purified, to remove monomeric crotonic acid, by extracting the copolymers with water at from 50.degree. to 120.degree. C and stirring the system, the flow energy of the water and the energy of stirring being chosen so that the polymer particles just remain suspended.

Purification of copolymers containing crotonic acid

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Dannstadt-Schauernheim, Germany

Ingo H Dorn