VERFAHREN ZUR KONTINUIERLICHEN HERSTELLUNG VON MIT KAUTSCHUK MODIFIZIERTEN POLYMERISATEN VON VINYLAROMATEN

A process, carried out without a diluent or in solution, in more than 2 reaction zones, for the continuous preparation of rubber-modified polymers of vinylaromatics, wherein a monomeric aromatic vinyl compound and an elastomeric polymer, in an amount of from 3 to 16% by weight based on the monomer, are polymerized, in the absence of a free radical initiator, but in the presence of a mercaptan as a chain transfer agent, at from 80 DEG to 180 DEG C. in a first reaction zone, with stirring, up to a maximum monomer conversion, Umax, given by the equation Umax=K-1 where K is the amount of rubber in % by weight based on monomer, and, in a second reaction zone, polymerization is continued, with stirring, to a conversion of up to about 50% by weight, after which a chain transfer agent is introduced in an amount of from 0.01 to 0.2% by weight, based on vinyl-aromatic monomer, and polymerization is continued, if appropriate in more than one reaction zone, up to a monomer conversion of less than 85% by weight. The polymer is treated in a devolatilization zone to remove vinyl-aromatic monomer and solvent, if any, and these constituents are recycled to the process. The process produces products which exhibit good gloss coupled with good mechanical properties, and which can be employed for conventional applications.