Continuous process for the preparation of bromochlorinated butyl rubber

Claim 1

A continuous process for bromochlorinating butyl rubber to contain from about 1.0 to about 3.0 weight % bromine and from about 0.05 to about 0.5 weight % of chlorine comprising the steps of: (a) providing in a first feed stream a solution of butyl rubber in a substantially inert solvent, said solution containing about 5 to about 30 weight percent of butyl rubber; (b) providing a second feed stream of bromine chloride in vapor form; (c) maintaining the relative flow rates of said first and second feed streams such that the ratio of moles of bromine chloride to moles of incorporated unsaturation in said butyl rubber is about 0.6 to 1 to about 1.5 to 1 while continuously transferring said first and second feed streams to a high intensity mixer and contacting said streams in said mixer to provide a homogeneous reaction mixture; (d) transferring said reaction mixture from step (c) to a second high intensity mixer, the mean transfer residence time being at least about 1 minute in order to complete the bromochlorination reaction; (e) simultaneously adding to said second mixer an aqueous solution of a basic neutralization feed stream resulting in a two phase, partially neutralized reaction mixture; (f) transferring said two phase reaction mixture to polymer recovery and drying means, the residence time of said transfer being at least about 1 minute in order to complete the neutralization reaction, the pH of said mixture maintained between about 7 and 13.