Patent ID: 7638583

Claim:
A continuous process of preparing brominated anionic styrenic polymer having a reduced volatile bromobenzene content which process comprises: A) concurrently feeding into a reaction zone components comprised of (i) a brominating agent, (ii) aluminum halide catalyst in which the halide atoms are bromine or chlorine or both, and (iii) anionic styrenic polymer having a GPC number average molecular weight in the range of about 2000 to about 30,000 in the form of a flowable solution in a solvent to form a reaction mixture, wherein said components are fed (1) individually as at least three separate feeds or (2) as at least two separate feeds, one feed of which contains no more than two of (i), (ii), and (iii), and another feed of which contains the third of (i), (ii), (iii) either individually or in combination with no more than one other of (i), (ii), and (iii), to thereby form a reaction mixture containing a liquid phase, and maintaining said reaction mixture at about 10° C. or less whereby bromination of anionic styrenic polymer occurs, said feeds of (1) or (2) hereof being fed as continuous or pulsed feeds and the rate at which the reaction mixture exits from the reaction zone in relation to the rate of the feeding of said feeds of (1) or (2) into the reaction zone being such that the volume of the traveling contents of the reaction zone remains substantially constant, the components being proportioned such that the amount of aluminum halide being fed is at about 0.8 mole percent or less in relation to the molar amount of aromatic monomer units in the anionic styrenic polymer being fed, and such that the dried brominated anionic styrenic polymer referred to in C) hereinafter will have a bromine content in the range of about 60 to about 71 wt %; B) deactivating the catalyst in, and washing away bromide ions and catalyst residues from 1) substantially the entire reaction mixture or 2) portions of the reaction mixture that have exited from the reaction zone; and C) recovering brominated anionic styrenic polymer product from the reaction mixture and drying such product whereby the dried brominated anionic styrenic polymer has a bromine content in the range of about 60 to about 71 wt % and a volatile bromobenzene content which is no more than about 600 ppm (wt/wt); the process being conducted such that the average residence time in said reaction zone in A) from initial contact of the reactants and catalyst in A) until deactivation of catalyst in B) is about 20 minutes or less.