PROCESS FOR RECOVERING BROMINATED STYRENE-BUTADIENE COPOLYMER FROM AN ORGANIC SOLVENT

摘要

Brominated styrene-butadiene copolymers are recovered from solution in an organic solvent. The copolymer solution is mixed with a liquid non-solvent in the presence of a suspension stabilizer to form a dispersion. The dispersion is heated to vaporize the organic solvent. This process produces precipitated copolymer particles having useful particle sizes, which can be easily used in downstream applications.

主权项

1. A process for recovering a brominated styrene-butadiene polymer from an organic solvent comprising
(1) forming a mixture of A) a solution of the brominated styrene-butadiene polymer dissolved in the organic solvent and B) a liquid non-solvent, in the presence of C) at least one organic suspension stabilizer, wherein: a) the brominated styrene-butadiene copolymer is soluble to the extent of no greater than 5 parts by weight per 100 parts by weight of the liquid non-solvent at the temperature at which step (3) is performed, b) solvent and liquid non-solvent are soluble in each other to the extent of no more than about 5 parts by weight of one per 100 parts by weight of the other at the temperature at which step (3) is performed, c) the liquid non-solvent has a boiling temperature at atmospheric pressure at least 10° C. greater than the lower of i) the boiling temperature of the organic solvent and ii), if the liquid non-solvent forms an azeotrope with the organic solvent which azeotrope has a lower boiling temperature than the organic solvent by itself, the boiling temperature of the azeotrope, d) the volume ratio of A) to B) in the mixture formed in step (1) is no greater than 1:1, and e) at the time step (1) is performed, the temperature of each of A) and B) is at least 10° C. below the lower of i) the boiling temperature of the organic solvent at atmospheric pressure and ii), if the organic solvent forms an azeotrope with the liquid non-solvent which azeotrope has a lower boiling temperature than the organic solvent by itself, the boiling temperature of such azeotrope; (2) agitating the mixture of A), B) and C) to form droplets of A) dispersed in B); (3) heating the dispersion formed in step (2) to a temperature below the boiling temperature of the liquid non-solvent but sufficient to vaporize the organic solvent by itself or as an azeotrope with the liquid non-solvent, such that the organic solvent vaporizes and is removed from the dispersion and the brominated styrene-butadiene copolymer precipitates to form particles, and (4) removing the precipitated particles of brominated styrene-butadiene copolymer from the liquid non-solvent.