Abstract: Disclosed is a process for the preparation of polyphenylene-sulfide resins, wherein an aromatic polyhalide compound is reacted with an alkali metal sulfide, or hydrogen sulfide and an alkali metal base, or an alkali metal hydrosulfide and an alkali metal base in the presence of an amide polar solvent. A polyphenylene-sulfide resin having a cyclic oligomer content lower than 1.5% by weight, as determined according to the methylene chloride extraction method, is obtained by (a) carrying out the reaction in the absence a polymerization assistant, (b) using the amide polar solvent in an amount not larger than 400 g per mole of the aromatic polyhalide compound, and (c) subjecting the polymerization liquid obtained by the reaction to hot solid-liquid separation at a temperature at least 50.degree. C. but lower than the boiling point of the solvent used, and washing the separated solid with the solvent used for the reaction, which is heated at a temperature at least 50.degree. C.

Abstract: Impurities can be removed from a polyphenylene sulfide resin with a high efficiency by heat-mixing a powdery phenylene sulfide resin with a solvent selected from (I) at least one solvent selected from dimethylsulfoxide, sulfolane, glycerol, ethylene glycol and diethylene glycol, (II) a mixed solvent of a solvent selected from dimethylsulfoxide, sulfolane, glycerol, ethylene glycol and diethylene glycol with an .alpha.-halogenated naphthalene or biphenyl, (III) a mixed solvent of the mixed solvent (II) or at least one solvent selected from benzyl alcohol, sulfolane and glycerol with N-methyl-2-pyrrolidone with water to bring the powder and the solvent sufficiently into contact with each other in the partially dissolved state, cooling and filtering the mixture, and washing the filter cake with a solvent incapable of dissolving the polyphenylene sulfide resin therein.