| 摘要 |
PROBLEM TO BE SOLVED: To produce a vinyl polymer while prolonging the interval of the periodic stop of operation and cleaning of machine, improving the productivity and saving the installation cost and energy consumption by recovering the solvent and unreacted monomer by distillation after the polymerization and reusing the recovered components as a polymerization medium solution. SOLUTION: In the solution polymerization of a monomer polymerization medium solution containing at least acrylonitrile, the solvent and the unreacted monomer are recovered from the polymer solution by distilling the solution after the polymerization reaction and the recovered components are used as the above monomer polymerization medium solution. Preferably, the solvent and unreacted monomer distilled from the solution are recovered by absorbing in a solution containing the monomer at a definite concentration maintained by the addition of an organic solvent, the recovery of the unreacted monomer is carried out by a continuous process and the recovered monomer polymerization medium solution is directly reused as the polymerization-feeding liquid without distilling and rectificating the solution.
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