Patent ID: 7504476

Claim:
A process for producing a poly(arylene sulfide) by polymerizing a sulfur source and a dihalo-aromatic compound in the presence of an alkali metal hydroxide in an organic amide solvent, which comprises: (1) a dehydration step of charging, into a reaction vessel, the organic amide solvent and the sulfur source comprising an alkali metal hydrosulfide alone or a mixture of 90 to 99.5 mol % of an alkali metal hydrosulfide and 0.5 to 10 mol % of an alkali metal sulfide, and a part of an overall charged amount of the alkali metal hydroxide as needed, and heating a mixture containing these components to discharge at least a part of a distillate containing water from the interior of the system containing the mixture to the exterior of the system, and (2) a polymerization step of mixing the mixture remaining within the system after the dehydration step with a dihalo-aromatic compound, heating a mixture for polymerization reaction containing these components to subject the sulfur source (hereinafter referred to as “available sulfur source”) and the dihalo-aromatic compound to a polymerization reaction, and adding the alkali metal hydroxide to the mixture for polymerization reaction continuously or in portions to control the pH of the mixture for polymerization reaction within a range of from 7 to 12.5 from the beginning to the end of the polymerization reaction, wherein in the polymerization step, the pH of the mixture for polymerization reaction is measured by collecting the reaction mixture, diluting it to 1/10 with ion-exchanged water and measuring the pH of the diluted solution.