| 摘要 |
PROBLEM TO BE SOLVED: To produce a brominated polystyrene particulate having a low residual solvent content by a simple and easy process while saving resources and energy by dissolving brominated polystyrene prepared by brominating polystyrene having a specified number average mol.wt. in a halogenous organic solvent, heating the resultant solution in a heating zone and jetting the solution out of the heating zone into a low pressure zone wherein the pressure is lower than in the heating zone to cause the flash evaporation of the solvent. SOLUTION: A brominated polystyrene obtained by brominating polystyrene having a number average mol.wt. of 10,000-500,000 and preferably a mol.wt. distribution of 1.0-3.0 is dissolved in a halogenous organic solvent preferably having a normal-pressure b.p. of 20-90 deg.C to give a solution preferably having a concentration of 5-40 wt.%. After heated in a heating zone, the solution is jetted out of the heating zone into a low pressure zone wherein the pressure is lower than in the heating zone to cause the flash evaporation of the solvent. In the heating zone, a long and narrow pipe through which the solution flows is heated from the outside by a heating medium. The pressure difference between the heating zone and the low pressure zone is preferably 3 kg/cm2 or higher. When the solution is jetted out of the heating zone, the temperature of the solution is preferably not lower than the b.p. of the solvent.
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