Process for producing poly(arylene sulfide), and poly(arylene sulfide) comprising contacting a wash liquid with an alkaline compound

A process for producing poly(arylene sulfide), the process comprising:

• a polymerization step of polymerizing a dihalogenated aromatic compound and at least one sulfur source selected from the group consisting of alkali metal sulfides and alkali metal hydrogen sulfides in an organic amide solvent to produce a polymer;
• a separation step of separating and recovering polymer from a reaction liquid containing the produced polymer after the polymerization step;
• a washing step of washing the recovered polymer with at least one washing liquid selected from the group consisting of water, an organic solvent, and a mixture solution of water and an organic solvent, wherein the organic solvent comprises acetone;
• and
• a separated liquid treatment step of bringing a separated liquid containing a wash waste liquid obtained after separating the polymer in the washing step and a polymer-separated liquid obtained after separating the polymer in the separation step into contact with an alkaline compound, wherein the step for treating the separated liquid is carried out until the pH of the separated liquid is in the range of 10.6 to 13.8, and wherein the separated liquid after the separated liquid treatment step is subjected to distillation and an organic solvent and/or an organic amide solvent is recovered and reused for the process for producing poly(arylene sulfide).