IMPROVED BROMINATION OF POLYMER

PROBLEM TO BE SOLVED: To provide an improved method for brominating a polymer, enabling improvement of the utilization rate of bromine in the process for brominating the polymer such as an isobutylene copolymer by using the mixture of an in active saturated paraffinic hydrocarbon with an inactive halogen-containing hydrocarbon as a solvent for the polymer. SOLUTION: This method for brominating a polymer comprises preparing the solution of (C) a (4-6C)isoolefin-(4-6C)conjugated diolefin copolymer in the mixture of (A) an inactive saturated paraffinic hydrocarbon with (B) an inactive halogen-containing hydrocarbon in an A/B volume ratio of approximately 90/10 to approximately 10/90 as a solvent, adding (D) bromine to the solution to react the component C with the component D at approximately 10-60 deg.C, and subsequently separating the brominated isoolefin-conjugated diolefin copolymer in which the component D is brominated in an amount of approximately 0.30-1.0 mole per mole of the conjugated diolefin in the component C. The component B includes a mono-, di or trihalogenated 1-6C paraffinic hydrocarbon or a halogenated aromatic hydrocarbon.