Patents Assigned to Toso Corporation
  • Patent number: 4789729
    Abstract: A polyarylene sulfide having a low content of electrolytic ions is economically recovered from a mixture consisting mainly of polyarylene sulfide and an alkali metal halide which mixture is obtained by reacting a polyhalogenated aromatic compound and an alkali metal sulfide containing water in an organic polar solvent, by dehydrating the mixture by distillation, mixing the dehydrated mixture with a solvent which is a poor solvent for both polyarylene sulfide and alkali metal halide and which is soluble in the organic polar solvent to prepare a slurry consisting essentially of the polyarylene sulfide and the alkali metal halide, subjecting the slurry to solid-liquid separation, washing the resultant cake with the poor solvent, drying the cake, adding water to the cake to wash away the alkali metal halide through dissolution, and subjecting the slurry to solid-liquid separation to recover polyarylene sulfide.
    Type: Grant
    Filed: November 25, 1987
    Date of Patent: December 6, 1988
    Assignees: Toso Corporation, Toso Susteel Co., Ltd.
    Inventors: Nobuo Nagira, Toshikazu Kato, Hiroshi Inoue