Patent ID: 7655748

Claim:
A process for producing a poly(arylene sulfide) by polymerizing a sulfur source and a dihalo-aromatic compound in an organic amide solvent, which comprises: (I) in a charging step, controlling charged amounts of the respective components in such a manner that the alkali metal hydroxide is present in a proportion of 1.00 to 1.09 mol per mol of the sulfur source, (II) in a polymerization step, polymerizing the sulfur source and the dihalo-aromatic compound in the presence of the alkali metal hydroxide in the organic amide solvent, (III) in a washing step, washing a polymer formed in the polymerization step repeatedly at least twice with a washing liquid composed of water, a hydrophilic organic solvent or a mixed liquid thereof, and at this time, washing the polymer with water or the mixed liquid at a final washing stage, and controlling washing conditions in such a manner that the pH of the washing liquid after the washing falls within a range of 8.0 to 11.0, and (IV) in a collecting step after the washing step, collecting a polymer having the following properties (a) to (d): (a) melt viscosity being 1 to 3,000 Pa·s as measured under conditions of a temperature of 310° C. and a shear rate of 1,216 sec −1 ; (b) pH being 7.0 to 12.0 as measured in a mixed solvent of water/acetone (volume ratio=2/1); (c) crystallization temperature being at most 220° C. as measured in the course of lowering the temperature of the polymer at a rate of 10° C./min from a molten state at a temperature of 340° C.; and (d) whiteness degree being at least 70 as measured in the form of a melt molded or formed product.